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expert reaction to press release giving topline results from Pfizer and BioNTech from their phase 2/3 trial looking at safety and antibody responses from their COVID-19 vaccine in children aged 5 to 11

The pharmaceutical company Pfizer have released a statement on the safety of their COVID-19 vaccine for children aged 5 to 11 following a phase 2/3 trial looking at safety and antibody responses.


Dr Peter English, Retired Consultant in Communicable Disease Control, Former Editor of Vaccines in Practice, Immediate past Chair of the BMA Public Health Medicine Committee, said:

“This press release reports on data from a phase 2/3 trial of the Pfizer BioNtech vaccine in children aged 5-12 years.

“It should be noted that there will be more information in full published papers (the press release states “Pfizer and BioNTech plan to submit data from the full Phase 3 trial for scientific peer-reviewed publication”); but we have become accustomed to the fact that commercial regulation requires companies to report such data as soon as possible, rather than awaiting a formal academic publication.  This limits our ability to interrogate the data and consider the methodology: we can expect much more information from peer-reviewed publications.

“We know from other vaccines (for other diseases) that adverse reactions are particularly common in adolescents: autoimmune type adverse reactions are more likely in this age group1,2.  Younger children, however, tend not to have as many such adverse reactions: vaccines are likely to be even safer in pre-adolescent children, as were studied here.

“This trial, with 2,268 children aged 5-11 years, were given a smaller (10 mcg) dose of the Pfizer-BioNtech vaccine.  They responded at least as well as 16-25 year-old controls, who were given a 30mcg dose.  Note that this is based on antibody responses: as children are less likely to develop symptomatic disease, it is likely to be harder, in the context of a clinical trial, to get robust data on vaccine efficacy, as the number of cases is likely to be small.  We may have to await implementation to see clinical effectiveness in terms of preventing serious disease.

“Similarly, while there are reasons to expect that children in this age group are less likely than others to have significant adverse reactions to vaccination, clinical trials are unable to detect or quantify rare adverse reactions.

“Younger children do get seriously unwell (from COVID-19), and some suffer serious complications, although they are less likely to do so than adolescents and adults3; and they also stand to benefit indirectly from vaccination, as we have discussed previously4.  Society also stands to benefit from reduced virus transmission.  Children were initially thought not to be likely to be infectious.  We now know that children can be infectious, and can transmit the infection to class-mates or to household members5-7; and this is all the more important now that the more infectious delta variant is prevalent.  If we are to achieve herd immunity, it may be necessary to vaccinate all school-age children.  (Children themselves may well benefit sufficiently for the risk-benefit of vaccination to be in favour of vaccinating them, even without taking the wider societal benefits into consideration.)

“The press release informs us that detailed data will be submitted to the US and EU regulators, seeking “emergency use authorisation” that will permit the vaccine to be added to vaccination programmes.  If this goes ahead, and some countries start to vaccinate this age group, we will start to accumulate data that will allow better estimates of real world effectiveness, and also to detect and quantify rates of uncommon adverse reactions.

“Now that the UK has left the EU, the UK’s MHRA will have to make its own decision on whether to issue an emergency use authorisation this age group.  This may introduce additional delays before the vaccine could be used for this age group in the UK.”

  1. Siegrist C-A, Lewis E, Eskola J, Evans S, Black S. Predicting vaccine scares following HPV immunization: A cohort study to define risks of coincidental associations with autoimmune diseases. European Society for Infectious Diseases. Porto, Portugal: Kenes, 2007(
  2. Siegrist C-A, Lewis EM, Eskola J, Evans SJW, Black SB. Human papilloma virus immunization in adolescent and young adults: a cohort study to illustrate what events might be mistaken for adverse reactions. Pediatr Infect Dis J 2007;26(11):979-984  PMID: 17984802. (
  3. Goldberg M. Covid Vaccines for Kids Can’t Wait. New York Times 2021; Updated 09 Aug 2021; Accessed: 2021 (12 Aug): (
  4. Riley E, MacDermott N, Clarke S, English PMB, Ward P. Expert reaction to JCVI updated advice on COVID-19 vaccination of children aged 12 to 15. Science Media Centre 2021; Updated 03 Sep 2021; Accessed: 2021 (11 Sep): (
  5. Hyde Z. Difference in SARS-CoV-2 attack rate between children and adults may reflect bias. Clin Infect Dis 2021. (
  6. Paul LA, Daneman N, Schwartz KL, Science M, Brown KA, Whelan M, et al. Pediatric household transmission of SARS-CoV-2 infection. medRxiv 2021:2021.03.29.21254565. ( or
  7. SAGE Children’s Task and Finish Group. Children’s Task and Finish Group: update to 17th December 2020 paper on children, schools and transmission. London: Paper presented at SAGE 80 on 11 Feb 2021 and finalised with amendments agreed by SAGE on 21 Feb 2021, 2021 (21 Feb); 1-33.


Dr David Elliman, Consultant Paediatrician, Great Ormond Street Hospital, said:

“The Pfizer and BioNTech  press release giving results from their phase 2/3 trial looking at safety and antibody responses in children aged 5 to 11, is just that – a press release.  There is little data to allow one to make any assessment of what the manufacturers claim.  The raw data should be made available.  Even if, on inspection, the data confirms that the vaccine gives a good immune response and has a good safety profile in the small number studied, this does not mean it should be used.  We do not know how commonly the rare side effect of myocarditis/pericarditis occurs at this age, ‘though we do know that the incidence is commoner in younger people than in the elderly.  We don’t know how severe it might be in this age group.  COVID infection is rarely serious in this group.  In view of its decision in relation to using the vaccine in 12-15 year olds, I cannot imagine the JCVI approving its use in younger children.  Based on past performance, they might refer it to the CMOs, but they do not have enough evidence to make a recommendation, either.”


All our previous output on this subject can be seen at this weblink:


Declared interests

Dr Peter English: “Dr English is on the editorial board of Vaccines Today: an unpaid, voluntary, position.  While he is also a member of the BMA’s Public Health Medicine Committee, this comment is made in a personal capacity.  Dr English sometimes receives honoraria for acting as a consultant to various vaccine manufacturers, most recently to Seqirus.”

Dr David Elliman: “No conflicts of interest.”

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