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expert reaction to lab study looking at activity of convalescent and vaccine serum against the Omicron variant

A study published in Nature looks at the activity of convalescent and vaccine serum against the Omicron variant of SARS-CoV-2 in the lab.


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

“This paper helps us to understand how the immune response to the Omicron variant differs from the response to other variants.

“The study is an in vitro study, using relatively small number of research subjects (10 in each group, apart from the convalescent group, which had 15 subjects).  We should remember that the relationship between measurable neutralising antibodies and clinical course of infection is not a simple one.  In general, antibodies are required to prevent initial infection; but cellular immunity – which may be maintained – is required to prevent serious illness.

“The article looks at how effectively antibodies produced by prior infection or vaccination will bind to and neutralise the omicron variant of the virus.  We can make some deductions about what this means in clinical and public health terms; but we need to be aware that these need to be supported by other forms of evidence.

“As the article points out, retained binding to the receptor binding domain can indicate that there is immunity – that “cognate B cells are present”.  This would suggest that, even if antibody levels are low, the immune system can very rapidly be stimulated to produce higher levels of antibodies, and the full cellular response.  This is consistent with the reduction in severe illness we have observed.

“The study also found that prior infection induced antibodies to parts of the virus which are not included in current mRNA and vector vaccines.  These may contribute to protection.

“Importantly, the study supports the view that a third dose of vaccine considerably improves the antibody response against omicron infection; and that people with prior immunity benefit from vaccination.

“The authors discuss issues that raise questions, as yet unanswered; some of these are probably mainly technical issues that should not worry us greatly when considering the impact of vaccination on controlling the pandemic.

“They also suggest that it will be important to develop omicron-specific vaccines.

“These findings fit with what we already know of SARS-CoV-2 generally, and with what we know of the Omicron variant in particular.”


Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, Respiratory Sciences, University of Leicester, said:

“Much like this earlier paper from France:, this US study: just confirms that omicron escapes vaccine-induced, natural immunity and monoclonal Ab therapy very effectively – the exact ‘fold reductions’ will differ between labs and experimental set-ups.

“But these studies do not examine the T-cell responses.  However, we know from our experience and knowledge with previous variants that these cell-mediated responses to vaccines and/or natural infection help to protect us against more severe disease and death.

“The bottom line is that boosting existing immunity (whether vaccine or naturally acquired) does help to protect against infection/reinfection to some degree – as well as boosting existing T-cell responses – all of which will help to protect us against omicron.  So getting these booster doses is important – especially if you are in one of the more vulnerable groups.

“However, we do not yet know how long these boosted levels of immunity will last.  Due to their cross-reactive/protective nature (as these vaccines were created to be specific to the earlier Wuhan virus), they are likely to wane relatively quickly.  Hence Israel’s introduction of a second booster for its elderly population (, and the UK may follow this later.

“Of course this strategy reduces the available vaccine doses, globally, for other countries who are yet to complete their initial two-dose vaccination programmes – and we also know that these unvaccinated and susceptible populations are where the next variants (pi, rho, sigma, etc.) are likely to arise.”



‘Activity of convalescent and vaccine serum against SARS-CoV-2 Omicron’ by Juan Manuel Carreño et al. was published in Nature on Friday 31 December 2021.

DOI: 10.1038/d41586-021-03846-z



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 (and its chair until Oct 2020), 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.”

None others received.

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