Peer-reviewed article
Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine (CoronaVac) in inadvertently vaccinated healthy children
Éder Gatti Fernandes, Giselle Ibette Silva López Lopes, Valéria Oliveira Silva, Rosemeire Yamashiro, Karen Cristina Rolim Madureira et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001Twenty-seven children aged 7 months to 5 years in Brazil were accidentally vaccinated with CoronaVac, an inactivated COVID-19 vaccine. Researchers monitored them for safety and immune response over 30 days. One child had mild symptoms but no serious adverse events occurred, and all children developed antibody responses to the vaccine.
Key points
- Only one child experienced a mild symptom after vaccination, with no other adverse events documented up to 30 days
- 19 of 27 children (70%) had positive serology on day 30, with antibody titers increasing from baseline to day 30
- 5 children (19%) had evidence of previous natural SARS-CoV-2 infection at baseline
- All children showed important increases in antibody titers by day 30 post-vaccination
- The study documents robust serological response to a single dose of CoronaVac in young children
Limitations
This was a small observational study of an accidental vaccination event without a comparison group or control arm. The sample size of 27 children is very limited and may not be representative of the broader population.
Abstract
Twenty-seven children aged seven months to 5 years were inadvertently vaccinated with a COVID-19 vaccine, the CoronaVac (Sinovac, China), an inactivated SARS-CoV-2 vaccine, in two different cities of Sao Paulo State, Brazil. After the event, these children were monitored by local pediatricians and serum samples were collected at the first visit and 30 days after vaccination and tested for SARS-CoV-2 S1 serology with Ortho total IgG anti-S1 protein and Cpass, an ACE2 receptor binding domain inhibition assay. Only one child had a mild symptom after vaccination, with no other adverse events documented up to the 30 days follow-up. Of 27 children tested 3-9 days after vaccination, 5 (19%) had positive serology suggesting a previous natural SARS-CoV-2 infection, with all 19 tested on day 30 after vaccination and presenting with positive tests, with an increment of antibody titers in those initially positive. A low Cpass binding inhibition was observed in the first collection in 11 seronegative cases, with high titers among those anti-S1 positive. All children showed an important increase in antibody titers on day 30. The event allowed the documentation of a robust serological response to one dose of CoronaVac in this small population of young children, with no major adverse effects. Although it was an unfortunate accident, this event may contribute with future vaccine strategies in this age group. The data suggest that CoronaVac is safe and immunogenic for children.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Single dose of CoronaVac (inactivated SARS-CoV-2 vaccine)
- Population
- 27 healthy children aged 7 months to 5 years who were inadvertently vaccinated
Key finding
Only 1 of 27 children (4%) had a mild symptom after vaccination; no other adverse events documented