Understanding SARS-CoV-2 Delta and Omicron variant transmission and vaccine impact in schools and child-care settings in Australia: a population-based study

Koirala, Archana; Winkler, Noni; Quinn, Helen; Gardiner, E.; Liu, B.; Forbes, J.; Sharpe, Claire C.; Tussenbroek, T. van; Wood, Nicholas; Macartney, Kristine

doi:10.1016/j.lanwpc.2023.100736

Cited by 4 publications

(3 citation statements)

References 21 publications

(33 reference statements)

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“…97 98 As the current COVID-19 vaccines were not available to children and adolescents until mid-2021 and they are non-sterilising, they did not contribute greatly to keeping schools open. 96 The newer bivalent vaccines have slightly improved effectiveness against infection with Omicron but are far from being sterilising. 99 Intranasal vaccines, many of which are in development, including candidates from AstraZeneca, Bharat Biotech, CanSinoBIO and the Gamaleya Center, have greater potential to prevent infection.…”

Section: Covid-19 Vaccine Equity and Opportunity Costsmentioning

confidence: 99%

“…Vaccinating children may have helped prevent infections if they were available for this age group early on in the pandemic, when they were more effective against infection prior to the emergence of the Omicron variant. 96 However, when Omicron emerged, the uptake of vaccines in high-risk groups in LMICs was still suboptimal and a priority. Additionally, vaccinating children would have greater benefits if the vaccines were able to prevent infection more robustly, thereby limiting community transmission.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Considerations for vaccinating children against COVID-19

Hart¹,

Ong²,

Chokephaibulkit³

et al. 2023

bmjpo

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COVID-19 vaccines have been introduced in children and adolescents in many countries. However, high levels of community transmission and infection-derived immunity make the decision to introduce COVID-19 vaccination of children in countries yet to do so particularly challenging. For example, other vaccine preventable diseases, including measles and polio, generally have far higher childhood morbidity and mortality in low-income and middle-income countries (LMICs) than COVID-19, and coverage with these vaccines has declined during the pandemic. Many countries are yet to introduce pneumococcal conjugate and rotavirus vaccines for children, which prevent common causes of childhood death, or human papillomavirus vaccine for adolescents. The Pfizer and Moderna COVID-19 vaccines that have been widely tested in children and adolescents have a positive risk-benefit profile. However, the benefit is less compared with other life-saving vaccines in this age group, particularly in LMICs and settings with widespread infection-derived immunity. The resources required for rollout may also pose a considerable challenge in LMICs. In this paper, we describe COVID-19 in children, with a focus on LMICs, and summarise the published literature on safety, efficacy and effectiveness of COVID-19 vaccination in children and adolescents. We highlight the complexity of decision-making regarding COVID-19 vaccination of children now that most of this low-risk population benefit from infection-derived immunity. We emphasise that at-risk groups should be prioritised for COVID-19 vaccination; and that if COVID-19 vaccines are introduced for children, the opportunity should be taken to improve coverage of routine childhood vaccines and preventative healthcare. Additionally, we highlight the paucity of epidemiological data in LMICs, and that for future epidemics, measures need to be taken to ensure equitable access to safe and efficacious vaccines before exposure to infection.

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Section: Covid-19 Vaccine Equity and Opportunity Costsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Considerations for vaccinating children against COVID-19

Hart¹,

Ong²,

Chokephaibulkit³

et al. 2023

bmjpo

View full text Add to dashboard Cite

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Real-world utilisation of SARS-CoV-2 rapid antigen testing to enable face-to-face learning in Australian schools, an ecological study

Koirala,

Winkler,

Sharpe

et al. 2024

Australian and New Zealand Journal of Public Health

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Seroincidence of SARS-CoV-2 infection prior to and during the rollout of vaccines in a community-based prospective cohort of U.S. adults

Nash,

Srivastava,

Shen

et al. 2023

Preprint

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LONG ABSTRACTBackgroundInfectious disease surveillance systems, which largely rely on diagnosed cases, underestimate the true incidence of SARS-CoV-2 infection, due to under-ascertainment and underreporting. We used repeat serologic testing to measure N-protein seroconversion in a well-characterized cohort of U.S. adults with no serologic evidence of SARS-CoV-2 infection to estimate the incidence of SARS-CoV-2 infection and characterize risk factors, with comparisons before and after the start of the SARS-CoV-2 vaccine and variant eras.MethodsWe assessed the incidence rate of infection and risk factors in two sub-groups (cohorts) that were SARS-CoV-2 N-protein seronegative at the start of each follow-up period: 1) the pre-vaccine/wild-type era cohort (n=3,421), followed from April to November 2020; and 2) the vaccine/variant era cohort (n=2,735), followed from November 2020 to June 2022. Both cohorts underwent repeat serologic testing with an assay for antibodies to the SARS-CoV-2 N protein (Bio-Rad Platelia SARS-CoV-2 total Ab). We estimated crude incidence and sociodemographic/epidemiologic risk factors in both cohorts. We used multivariate Poisson models to compare the risk of SARS-CoV-2 infection in the pre-vaccine/wild-type era cohort (referent group) to that in the vaccine/variant era cohort, within strata of vaccination status and epidemiologic risk factors (essential worker status, child in the household, case in the household, social distancing).FindingsIn the pre-vaccine/wild-type era cohort, only 18 of the 3,421 participants (0.53%) had>1 vaccine dose by the end of follow-up, compared with 2,497/2,735 (91.3%) in the vaccine/variant era cohort. We observed 323 and 815 seroconversions in the pre-vaccine/wild-type era and the vaccine/variant era and cohorts, respectively, with corresponding incidence rates of 9.6 (95% CI: 8.3-11.5) and 25.7 (95% CI: 24.2-27.3) per 100 person-years. Associations of sociodemographic and epidemiologic risk factors with SARS-CoV-2 incidence were largely similar in the pre-vaccine/wild-type and vaccine/variant era cohorts. However, some new epidemiologic risk factors emerged in the vaccine/variant era cohort, including having a child in the household, and never wearing a mask while using public transit. Adjusted incidence rate ratios (aIRR), with the entire pre-vaccine/wild-type era cohort as the referent group, showed markedly higher incidence in the vaccine/variant era cohort, but with more vaccine doses associated with lower incidence: aIRRun/undervaccinated=5.3 (95% CI: 4.2-6.7); aIRRprimaryseriesonly=5.1 (95% CI: 4.2-7.3); aIRRboostedonce=2.5 (95% CI: 2.1-3.0), and aIRRboostedtwice=1.65 (95% CI: 1.3-2.1). These associations were essentially unchanged in risk factor-stratified models.InterpretationIn SARS-CoV-2 N protein seronegative individuals, large increases in incidence and newly emerging epidemiologic risk factors in the vaccine/variant era likely resulted from multiple co-occurring factors, including policy changes, behavior changes, surges in transmission, and changes in SARS-CoV-2 variant properties. While SARS-CoV-2 incidence increased markedly in most groups in the vaccine/variant era, being up to date on vaccines and the use of non-pharmaceutical interventions (NPIs), such as masking and social distancing, remained reliable strategies to mitigate the risk of SARS-CoV-2 infection, even through major surges due to immune evasive variants. Repeat serologic testing in cohort studies is a useful and complementary strategy to characterize SARS-CoV-2 incidence and risk factors.SHORT ABSTRACTThis study used repeat serologic testing to estimate infection rates and risk factors in two overlapping cohorts of SARS-CoV-2 N protein seronegative U.S. adults. One mostly unvaccinated sub-cohort was tracked from April to November 2020 (pre-vaccine/wild-type era, n=3,421), and the other, mostly vaccinated cohort, from November 2020 to June 2022 (vaccine/variant era, n=2,735). Vaccine uptake was from 0.53% and 91.3% in the pre-vaccine and vaccine/variant cohorts, respectively. Corresponding seroconversion rates were 9.6 and 25.7 per 100 person-years. In both cohorts, sociodemographic and epidemiologic risk factors for infection were similar, though new risks emerged in the vaccine/variant era, such as having a child in the household. Despite higher incidence rates in the vaccine/variant cohort, vaccine boosters, masking, and distancing likely reduced infection risk, even through major variant surges. Repeat serologic testing in cohorts is a useful and complementary strategy to characterize incidence and risk factors.FundingThe work was supported by the CUNY Institute for Implementation Science in Population Health, the U.S. National Institutes of Allergy and Infectious Diseases (NIAID), Pfizer, Inc., and the U.S. National Institute of Mental Health (NIMH).

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Understanding SARS-CoV-2 Delta and Omicron variant transmission and vaccine impact in schools and child-care settings in Australia: a population-based study

Cited by 4 publications

References 21 publications

Considerations for vaccinating children against COVID-19

Considerations for vaccinating children against COVID-19

Real-world utilisation of SARS-CoV-2 rapid antigen testing to enable face-to-face learning in Australian schools, an ecological study

Seroincidence of SARS-CoV-2 infection prior to and during the rollout of vaccines in a community-based prospective cohort of U.S. adults

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