From the beginning of the coronavirus disease 2019 (COVID-19) pandemic it became evident that children infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain mostly asymptomatic or mildly symptomatic. We reviewed the epidemiologic and clinical features of children with SARS-CoV-2 infection.

Nature looks at how the trials will account for differences in children’s immune systems and susceptibility to COVID-19, compared with those of adults, as well as the added safety precautions that surround medical research in kids. I want to see them protected,” says James Conway, a paediatric infectious-disease specialist and vaccine researcher at the University of Wisconsin–Madison. Evidence is building that vaccines might block transmission of SARS-CoV-2 , so vaccinating children could have beneficial knock-on effects in the wider community.

In The Lancet Infectious Diseases , Bihua Han and colleagues reported the results of a double-blind, randomised, controlled, phase 1/2 clinical trial, which showed that the inactivated COVID-19 vaccine (CoronaVac) had good safety, tolerability, and immunogenicity in youths aged 3–17 years.2 Han B Song Y Li C et al. Summary Full Text Full Text PDF Scopus (5) Google Scholar the Pfizer-BioNTech vaccine showed a similar trend: vaccinees developed higher titres of neutralising antibodies in children aged 12–15 years than in those aged 16–25-years. Children's strong response means that they are more likely to develop immune overactions than adults, such as fever and allergy, so COVID-19 vaccine for children should balance a protective immune response and side-effects.

Shay , MD 1 On October 29, 2021, the Food and Drug Administration (FDA) amended the Emergency Use Authorization (EUA) for Pfizer-BioNTech COVID-19 (BNT162b2) mRNA vaccine to expand its use to children aged 5–11 years, administered as 2 doses (10 μ g, 0.2mL each) 3 weeks apart ( 1 ). As of December 19, 2021, only the Pfizer-BioNTech COVID-19 vaccine is authorized for administration to children aged 5–17 years ( 2 , 3 ). In preauthorization clinical trials, Pfizer-BioNTech COVID-19 vaccine was administered to 3,109 children aged 5–11 years; most adverse events were mild to moderate, and no serious adverse events related to vaccination were reported ( 4 ). To further characterize safety of the vaccine in children aged 5–11 years, CDC reviewed adverse events after receipt of Pfizer-BioNTech COVID-19 vaccine reported to the Vaccine Adverse Event Reporting System (VAERS), a passive vaccine safety surveillance system co-managed by CDC and FDA, and adverse events and health impact assessments reported to v-safe, a voluntary smartphone-based safety surveillance system for adverse events after COVID-19 vaccination,* during November 3–December 19, 2021. Myocarditis is a rare and serious adverse event that has been associated with mRNA-based COVID-19 vaccines; reporting rates for vaccine-associated myocarditis appears highest among males aged 12–29 years ( 8 ). To date, myocarditis among children aged 5–11 years appears rare; 11 verified VAERS reports have been received after administration of approximately eight million vaccine doses, and, in an active vaccine safety surveillance system, no chart-confirmed reports of myocarditis were observed during the 1–21 days or 1–42 days after 333,000 vaccine doses were administered to children of the same age (6 ) These cases appear consistent with other reports of myocarditis after mRNA COVID-19 vaccination regarding time to symptom onset and a mild clinical course (9 ). Two deaths after Pfizer-BioNTech COVID-19 vaccine were reported for children with multiple chronic medical conditions; on initial review, no data were found that would suggest a causal association between death and vaccination.

Women’s level of worry about COVID-19 in the US and Russia was comparable to that in lower incidence countries (Australia and New Zealand) (Fig. 4 a). Despite this variation in concern, self-reported compliance with local mask-wearing regulations was above 75% in all countries (Fig. 4 b). Most responders trusted health science in general (Figure S2a) and were satisfied with public health authorities in their countries for their performance in controlling the pandemic (Figure S3a); although the trust and satisfaction level varied among countries (Figures S2b, S3b, 5 a, b). Though 74.2% of women felt informed on the development of a COVID-19 vaccine (Figure S4), 27.7% did not follow COVID-19 news in any form (TV, radio, newspaper, news websites, social media). Fig. 4 Perceptions of COVID-19 among pregnant women and mothers of school-aged children. a Worries about COVID-19 (n = 17,844). b Mask-wearing compliance (n = 17,803) Full size image Fig. 5 Public trust and satisfaction among pregnant women and mothers of school-aged children. a Trust that public health agencies would provide accurate vaccine safety information (n = 17,839). b Satisfaction on responsiveness of government policies to participants concerns during the COVID-19 pandemic (n = 17,838) Full size image Attitudes towards vaccines The majority of women in the 16 countries believed it was important for their own country to have a COVID-19 vaccine (85.8%) (Figure S1a), and for most people in their own country to get vaccinated (82.6%) (Figure S1b). Perceptions on the importance of childhood vaccinations were also positive, with 92.0% of women responding that vaccines can protect children from serious infectious diseases (Figure S5b). In addition, 49.4%, reported vaccination for influenza in the past year. As more specific data for these vulnerable groups become available, it will provide opportunities to influence key predictors we identified and enhance public trust in the rigorous approval of upcoming vaccines [21 ]. Current acceptance levels of a COVID-19 vaccine among most of the high-income countries included in this study are insufficient to meet the requirements for community immunity of at least 75%. COVID-19 vaccine acceptance and its predictors among pregnant women and mothers of young children vary globally and, therefore, vaccination campaigns for this population should be specified for each country in order to attain the largest impact.

However, since the introduction of nasal flu jabs for school going children (2–17 years) in UK about a decade ago [7 , 8 ], Public Health England were able to achieve the desired outcome from mass flu immunisation in UK, such as preventing children from catching the infection in the first instance, blocking community transmission that has also reduced the adverse impact on children education and schools etc., boosting the vaccine efficacy to over 87% in 2019 [27 ]. Several clinical trials confirmed the superior efficacy of nasal flu vaccine over the injectable flu vaccine in preventing infections in children from as young as 6 months to 17 years [18 ]. In influenza season 2002–2003, studies D153–P514 and D153–P515 in Europe [28 ] involving 2,085 (6 months to 6 years) and 2,211 children (6–17 years) resulted in 52.7 and 34.7% fewer flu cases than the injectable group, respectively. The other nasal COVID vaccine candidates under development include products from CanSinoBIO [11 ], Bharat Biotech [12 ] and Sputnik V [13 ] (all three had their injectable COVID vaccines successfully deployed across the world). In addition, there is a candidate from National Taiwan University Hospital under developmet [14 ], and yet another nasal vaccine is jointly developed by the lnfectiology and Public Health (ISP) research unit and the Université de Tours in France [15 ]. Conclusions The nasal COVID vaccines have already evidenced to provide the mucosal antibodies (IgA), i.e., the immune protection in the upper respiratory tract and are likely to protect the children from contracting the virus in the first instance and, therefore, will also prevent community transmission.

Email: christiane.eberhardt@hcuge.ch Contribution: Conceptualization (equal), Writing - original draft (lead), Writing - review & editing (supporting) Search for more papers by this author Claire-Anne Siegrist , Claire-Anne Siegrist orcid.org/0000-0001-7984-8669 Center for Vaccinology, University Hospitals of Geneva, Geneva, Switzerland Departments of Pathology-Immunology and Pediatrics, Faculty of Medicine, University of Geneva, Geneva, Switzerland Contribution: Conceptualization (equal), Writing - original draft (supporting), Writing - review & editing (lead) Search for more papers by this author First published: 28 October 2020 Citations: 5 Abstract Tremendous efforts are undertaken to quickly develop COVID-19 vaccines that protect vulnerable individuals from severe disease and thereby limit the health and socioeconomic impacts of the pandemic. Compared to adults, the incidence and disease severity of COVID-19 are low in children, and despite their infectiveness, their role in disease propagation is limited.

Epidemiological burden of COVID-19 in children Increasing cases and incidence Although few pediatric cases were reported initially during the COVID-19 pandemic, retrospective data demonstrate that children were indeed infected early on [4 , 5 ]. In general, children with COVID-19 are asymptomatic or have mild to moderate symptoms and less likely to be tested. Therefore, relying on hospitalization or testing rates alone underestimates the true disease burden [6 , 7 ]. Li et al. found that the SARS-CoV-2 infection rate of children at the early stage of the epidemic in Wuhan was 2.4%–3.1%, with the overall infection rate of 4.4% [8 ]. Subsequent studies have shown consistently that children and adolescents are as likely to be infected as the adult population [9 ,10 ,11 ]. As of August 26, 2021, about 4.80 million children aged