The Medical Journal of Australia - Pre-print - 20 May 2021

 
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The Medical Journal of Australia – Pre-print – 20 May 2021

Impact of the COVID-19 pandemic on vaccination uptake in Victorian children,

adolescents and older adults

Brynley P Hull
Research Fellow
National Centre for Immunisation Research and Surveillance Centre (NCIRS)
Children's Hospital Westmead
Westmead, New South Wales, Australia

Alexandra J Hendry
Senior Research Officer - Coverage & Surveillance
Children's Hospital at Westmead
National Centre for Immunisation Research & Surveillance
Westmead, New South Wales, Australia

Aditi Dey
Manager Surveillance
National Centre for Immunisation Research and Surveillance of Vaccine Preventable
Diseases – Surveillance
Westmead, New South Wales, Australia

Senior Lecturer
University of Sydney
Discipline of Paediatrics and Child Health
Camperdown, New South Wales, Australia

Kerin Bryant
Principal Project Officer
Victoria Department of Health and Human Services
Health Protection Branch
Melbourne, Victoria, Australia

Catherine Radkowski
Manager, Immunisation Projects and Policy
Victoria Department of Health and Human Services
Communicable Diseases, Health Protection Branch
Melbourne, Victoria, Australia

Stephen Pellissier
Manager, Immunisation
Victoria Department of Health and Human Services
Health Protection Branch
Melbourne, Victoria, Australia
The Medical Journal of Australia – Pre-print – 20 May 2021

Kristine Macartney
Director
Children's Hospital at Westmead
National Centre for Immunisation Research and Surveillance (NCIRS)
Westmead, New South Wales, Australia

Professor
University of Sydney
Department of Paediatrics and Child Health
Sydney, New South Wales, Australia

Frank H Beard
Staff Specialist - Public Health Physician
The Children's Hospital at Westmead
National Centre for Immunisation Research and Surveillance
Westmead, New South Wales, Australia

Senior Lecturer
School of Public Health
University of Sydney
Sydney, New South Wales, Australia

Competing interests: No relevant disclosures
The Medical Journal of Australia – Pre-print – 20 May 2021

Abstract (50 words)

We analysed Australian Immunisation Register data to assess COVID-19 pandemic impact
on vaccination uptake in Victoria in 2020. No impact was seen in young children. HPV
vaccinations were 18% lower in 2020 than 2019 for dose 2 but similar for dose 1, and zoster
vaccinations in 70-year-olds were 4% lower.
The Medical Journal of Australia – Pre-print – 20 May 2021

Main text (799 words)

The coronavirus disease 2019 (COVID-19) pandemic and associated measures to reduce
spread of disease have impacted routine immunisation in many countries.1-3

Strict physical distancing and movement restrictions (stage 3 ‘lockdown’ measures) were
implemented nationally from 23 March 2020, with many healthcare providers pivoting to a
telehealth-based model. While previous analyses found no impact of the first pandemic wave
on uptake of childhood vaccinations due up to July 2020, at either national or state/territory
level,4 these analyses did not assess potential impacts of the more stringent measures,
particularly ‘stage 4’ lockdowns in Melbourne, implemented in Victoria from early August to
late October 2020, due to a second epidemic wave. Additionally, no analyses have reported
on impact of the shift to remote learning on adolescent vaccination, usually delivered on
school premises in Australia, or uptake in older adults. Using Australian Immunisation
Register (AIR) data as of 28 February 2021, we compared vaccination uptake in Victoria in
2020 with 2019.

Monthly uptake for selected vaccines due at 2, 4 and 12 months of age was assessed by
Indigenous status (all/Indigenous). One-month wide birth cohorts were used with uptake
assessed at one month after vaccine due, i.e. earlier than standard vaccination coverage
reporting (6-12 months after due).5 Proportion of children vaccinated was calculated using
number vaccinated with the relevant vaccine as numerator and number registered on AIR as
denominator. Monthly counts of human papillomavirus (HPV) vaccinations (dose 1 and 2) in
adolescents aged 11-14 years, and zoster vaccinations in adults aged 70 years, were
calculated by Indigenous status. As we did not sample a population but analysed AIR data
for the entire Victorian population within the specified age groups, we considered calculation
of confidence intervals to not be required.

No substantial impact of either stage 3 or 4 lockdown restrictions was seen on uptake in
young children of diphtheria-tetanus-pertussis-containing vaccine (dose 1 due at 2 months of
age), 13-valent pneumococcal conjugate vaccine (dose 2 due at 4 months of age), and
measles-mumps-rubella vaccine (12 months of age), in either all (Box 1A) or Indigenous
(Box 1B) children.

HPV dose 1 vaccinations in adolescents were lower in March and April 2020 (20.0% and
79.3%, respectively), when students were learning from home, but substantially higher
(96.4%-801.6%) in all subsequent months than in 2019, including August-October when
students were also learning from home (Box 2A). HPV dose 2 vaccinations were lower in
March and April 2020 (6.4% and 12.9%, respectively), and August-October (47.2%-61.1%),
but higher in other months, notably December (352.8%). The total number of HPV
The Medical Journal of Australia – Pre-print – 20 May 2021

vaccinations was 0.2% lower for dose 1 (but 38.6% higher for Indigenous adolescents) and
17.6% lower for dose 2 (10.3% higher for Indigenous) in 2020 than 2019.

Zoster vaccine doses recorded for adults aged 70 years were substantially lower in May,
August and September 2020 (45.2%, 42,2% and 23.4%, respectively), but higher in March
(33.6%; likely due to earlier rollout of the influenza vaccination program), November (46.5%)
and December (67.4%), than in in 2019 (Box 2B). The total number of zoster vaccinations
recorded for adults aged 70 years was 3.8% lower (21.5% for Indigenous) in 2020 than
2019.

Study limitations include that substantial underreporting of zoster vaccination in older adults
to the AIR has previously been identified,6 so if reporting completeness was greater in 2020
than 2019 we may have underestimated the impact on uptake. As we assessed vaccination
uptake for young children earlier than usual, it will be important to monitor any impacts in
populations where timeliness of vaccination is a known issue e.g. Indigenous children.

In summary, we found no evidence of impact of the pandemic and associated measures on
vaccination uptake in Victoria in young children, despite the longest and most restrictive
pandemic response measures in Australia. This continued strong uptake in Victoria, and
Australia more broadly,4 is likely due to consistent messaging by health authorities that
immunisation is an essential health service, efforts by vaccination providers to provide
COVID-19 safe services, continued engagement of parents/carers, and lower disease rates
than many other countries. However, there were substantial impacts on HPV dose 1
vaccination in adolescents in the first epidemic wave, with flow-on effect to dose 2
vaccinations later in 2020, given the minimum 6-month interval between doses. Pleasingly,
no similar impact of the second epidemic wave was seen, likely due to the Victorian health
department’s engagement with local councils to facilitate alternative program delivery
arrangements, and with general practitioners to promote catch-up vaccination, and
mainstream and social media messaging and additional resources for providers and
parents.7 We also found some impact on zoster vaccination uptake in older adults,
particularly Indigenous, which may reflect greater propensity to delay routine vaccination due
to concerns about COVID-19 infection risks. Overall our findings demonstrate resilience of
the Victorian immunisation delivery system in the face of unprecedented social and
healthcare disruption.
The Medical Journal of Australia – Pre-print – 20 May 2021

Box 1: Vaccination uptake at 2-, 4- and 12-month age milestones for selected vaccine
doses8, assessed 1 month after vaccines due for successive 1-month-wide birth
cohorts; all children (A) and Indigenous children (B), Victoria, 2019-2020*

A (all children)

B (Indigenous children)
              100
                                                              90.2
              90    85.7                                                                                     91.2
                                                               82.8                                                        89.2
              80                                                                                              83.5
                    80.4
                                                                                                                          76.6
              70                                              74.6
 Uptake (%)

                                                                               End                           66.1
                    65.2                                                     Stage 3
              60                                                             lockdo
                                                                               wn-
                                                                              26/5-
                                                                                                              End Stage   60.1
                                                                                                                  4/3
                                                                    Start      9/6†                           lockdow n
              50                                                  Stage 3
                                                                                           Start
                                                                                                                 - 12-
                            DTP-containing vaccine - dose 1      lockdow n
                                                                   - 23/3                Metro &
                                                                                                                26/10‡
                                                                                          Mitchell
              40            13vPCV- dose 2                                                 Shire
                                                                                         Stage 3
                                                                                        lockdown
                            MMR vaccine - dose 1                                           - 8/7
              30
                                                                                                    Start
                                                                                                    Metro
              20                                                                                 Stage 4 &
                                                                                                  Regional
                                                                                                   Stage 3
                                                                                                 lockdow n
              10                                                                                     -2/8

               0
                    Jan

                    Jan
                    Dec

                    Dec
                    Nov

                    Nov
                    Jun

                    Feb
                    Feb

                    Apr

                     Jul
                    Aug

                    Oct

                    Oct
                    Apr

                    Jun
                     Jul
                    Aug
                    Mar

                    Mar
                    May

                    Sep

                    May

                    Sep

                                  2019                                                 2020
                                              Month vaccines due
The Medical Journal of Australia – Pre-print – 20 May 2021

* Vaccination uptake in this figure represents timely uptake of selected doses and does not equate to vaccination
coverage as usually assessed (at 6-12 months after dose due capturing catch-up vaccinations well beyond the
first month as assessed here)
† Partial return to school on 26 May; full return on 9 June 2020.
‡ Stage 3 ended in regional areas on 12 October 2020; and metropolitan areas on 26 October 2020.
DTP = diphtheria-tetanus-pertussis
13vPCV = 13-valent pneumococcal conjugate vaccine
MMR = measles-mumps-rubella
The Medical Journal of Australia – Pre-print – 20 May 2021

Box 2: Monthly dose counts recorded on the AIR8 for HPV vaccinations (dose 1 and 2)
in adolescents aged 11-14 years (A) and zoster vaccinations in adults aged 70 years
(B), Victoria, 2019-2020

A (HPV)

B (zoster)

                                                  3500
 Number of zoster vaccine doses recorded on AIR

                                                                                                                   End Stage
                                                                                                                   3 lockdown
                                                                                                   Start Stage 3   - 26/5-9/6*
                                                                                                    lockdow n -
                                                                 2932                                  23/3                 Start Metro Start Metro
                                                  3000                                                                       & Mitchell Stage 4 &
                                                                                                                                                        End Stage
                                                                                                                               Shire      Regional         4/3
                                                                                                                              Stage 3     Stage 3
                                                                                                                            lockdow n - lockdow n -    lockdow n -
                                                                                                                                8/7         2/8         12-26/10†
                                                  2500

                                                  2000       1876                                            1927

                                                                                                   1570            1606
                                                                                                                                                         1494
                                                  1500              1293                                                  1336                               1379
                                                          1175                 1175
                                                                                                                                                  1088
                                                                                      985
                                                  1000
                                                                                                                                                 755
                                                                                                                                          679

                                                   500

                                                     0
                                                         Dec
                                                         Jan

                                                         Jan

                                                         Dec
                                                         Aug

                                                         Nov
                                                         Apr

                                                          Jul

                                                         Apr

                                                         Aug

                                                         Nov
                                                         Oct
                                                         Feb

                                                         Oct
                                                         Jun

                                                         Feb

                                                         Jun
                                                          Jul
                                                         Mar

                                                         May

                                                         May
                                                         Sep

                                                         Mar

                                                         Sep

                                                                        2019                                                2020
                                                                                       Month of vaccination
The Medical Journal of Australia – Pre-print – 20 May 2021

* Partial return to school on 26 May; full return on 9 June 2020.
† Stage 3 ended in regional areas on 12 October 2020; and metropolitan areas on 26 October 2020.
HPV = human papillomavirus

LINE GRAPHS

Box 2: Monthly dose counts recorded on the AIR8 for HPV vaccinations (dose 1 and 2)
in adolescents aged 11-14 years (A) and zoster vaccinations in adults aged 70 years
(B, Victoria, 2019-2020

A (HPV)

                                               40000
                                                          37803                   Dose 1
                                                                                             Start Stage    End Stage
                                                                                  Dose 2
 Number of HPV vaccine doses recorded on AIR

                                                                                             3 lockdow n    3 lockdow n
                                               35000                                            - 23/3      - 26/5-9/6*

                                                                              31573                                  Start        Start
                                                                                           30257                    Metro &      Metro
                                                                                                                                               End
                                               30000                                                                Mitchell
                                                                                                                     Shire
                                                                                                                                Stage 4
                                                                                                                                   &
                                                                                                                                           Stage 4/3
                                                                                                                    Stage 3     Regional   lockdow n
                                                                                                                  lockdown -    Stage 3       - 12-
                                                                                                                      8/7      lockdown      26/10†
                                               25000                                                                              -2/8

                                               20000
                                                                                                                                                17490

                                               15000
                                                                              12269
                                               10000         9512                                          9124

                                                5000                                                                                                   6212
                                                                           3318

                                                   0
                                                       Jan

                                                       Jan
                                                       Dec

                                                       Dec
                                                       Nov

                                                       Nov
                                                       Feb

                                                       Jun

                                                       Feb

                                                       Jun
                                                       Oct
                                                       Apr

                                                        Jul
                                                       Aug

                                                       Apr

                                                        Jul

                                                       Oct
                                                       Aug
                                                       Mar

                                                       May

                                                       Sep

                                                       Mar

                                                       May

                                                       Sep

                                                                    2019                                           2020
                                                                              Month of vaccination
The Medical Journal of Australia – Pre-print – 20 May 2021

B (zoster)

                                                  3500
 Number of zoster vaccine doses recorded on AIR

                                                                                                               End
                                                                                                             Stage 3
                                                                                             Start Stage   lockdow n
                                                                                             3 lockdow n     - 26/5-
                                                               2932                              - 23/3        9/6*     Start     Start
                                                  3000                                                                Metro &     Metro
                                                                                                                       Mitchell Stage 4 &
                                                                                                                                            End Stage
                                                                                                                                                4/3
                                                                                                                        Shire   Regional
                                                                                                                      Stage 3               lockdow n
                                                                                                                                 Stage 3       - 12-
                                                                                                                     lockdow n lockdow n
                                                                                                                        - 8/7                 26/10†
                                                  2500                                                                             -2/8

                                                                                                     1927
                                                  2000

                                                                                                                                              1494
                                                  1500

                                                  1000
                                                                        900                                                     679
                                                                                     824

                                                   500

                                                     0
                                                         Jan

                                                         Jan
                                                         Dec

                                                         Dec
                                                         Nov
                                                         Feb

                                                         Apr

                                                         Feb

                                                         Apr

                                                         Nov
                                                         Jun
                                                          Jul

                                                         Oct
                                                         Aug

                                                         Jun
                                                          Jul

                                                         Oct
                                                         Aug
                                                         Mar

                                                         Sep

                                                         Mar

                                                         Sep
                                                         May

                                                         May          2019                                         2020
                                                                              Month of vaccination
* Partial return to school on 26 May; full return on 9 June 2020.
† Stage 3 ended in regional areas on 12 October 2020; and metropolitan areas on 26 October 2020.
HPV = human papillomavirus
The Medical Journal of Australia – Pre-print – 20 May 2021

References

1.       World Health Organization. WHO and UNICEF warn of a decline in vaccinations during
COVID-19. 2020. Available from: https://www.who.int/news/item/15-07-2020-who-and-unicef-
warn-of-a-decline-in-vaccinations-during-covid-191 December 2020.
2.       Santoli JM, Lindley MC, De Silva MB, et al. Effects of the COVID-19 Pandemic on Routine
Pediatric Vaccine Ordering and Administration — United States, 2020. MMWR Morb Mortal Wkly
Rep. 2020;69:591-3.
3.       Public Health England. Impact of COVID-19 on childhood vaccination counts to week 43,
and vaccine coverage to September 2020in England: interim analyses. London: Public Health
England; 2020. Available from:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file
/933545/hpr2120_chldhd-vc_wk43.pdf Accessed 2020 24 November 2020.
4.       National Centre for Immunisation Research and Surveillance. COVID-19: Impact on routine
childhood vaccination uptake in Australia. 2020. Available from:
https://www.ncirs.org.au/sites/default/files/2020-11/COVID-
19_Impact_Analysis_Final%20Report.pdf1 December 2020.
5.       Hull B, Hendry A, Dey A, et al. Immunisation Coverage Annual Report 2019. Commun Dis
Intell. 2021 Mar 31;45.
6.       Hull B, Hendry A, Dey A, et al. Exploratory analysis of the first 2 years of adult vaccination
data recorded on AIR. Sydney: National Centre for Immunisation Research and Surveillance; 2019.
Available from: http://ncirs.org.au/sites/default/files/2019-
12/Analysis%20of%20adult%20vaccination%20data%20on%20AIR_Nov%202019.pdf Accessed 2020
3 December 2020.
7.       Victorian Government Department of Health and Human Services. Secondary school
immunisation program 2020 during COVID: Advice for parents and guardians – 3 August 2020. 2020.
Available from: https://www2.health.vic.gov.au/about/publications/factsheets/sec-school-
immunisation-2020-covid-fs-parents3 December 2020.
8.       Australian Government - Services Australia. Australian Immunisation Register. Canberra:
Australian Government - Services Australia; 2020. Available from:
https://www.servicesaustralia.gov.au/individuals/services/medicare/australian-immunisation-
register Accessed 2021 18/05/2021.
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