Professor Chris Whitty said it was ‘likely’ that some people, particularly those who are vulnerable to the virus, would have to be revaccinated to top up immunity, or potentially if the virus shifts.
Giving evidence to MPs, England’s chief medical officer said that the COVID-19 vaccine would provide ‘short- to medium-term protection’ - but admitted that it was unknown how long this would last.
Professor Whitty's comments suggest that annual COVID-19 vaccination campaigns could become a reality for the NHS, as staff roll out the first jabs this week. However, he said more information on the vaccine's ‘length of effect, efficacy, safety’ was needed before a decision could be made.
Responding to questions on COVID-19 vaccinations, Professor Whitty said: ‘Do we need to re-vaccinate people and if so when? We know that these are very good vaccines to provide short- to medium-term protection, but we don’t know how long that lasts. It might last for a very long time, it might last for, you know, nine months. I think it’s more likely to be somewhere between those two.
‘Therefore, it’s likely that we could have a situation where we have to be in a position to revaccinate, particularly the people who are most vulnerable. So I think all of these, we will have to rethink about once all the information comes out on length of effect, efficacy, safety and so on and what vaccines suit what people.'
Professor Whitty said it was unclear whether people would have to be re-vaccinated and how often, but explained why annual campaigns may be needed.
He said one scenario where re-vaccination could be needed was because 'the immune system wanes' - so further doses of the same vaccine are administered to top up immunity.
The CMO added: 'The other is the genetic thing that you are targeting the vaccine against shifts, the infection evolves around the vaccine. This is what happens with flu - then you have to re-formulate the vaccine and use a slightly different vaccine to deal with the new version.’
Professor Whitty said he expected to have a portfolio of three or four vaccines by the middle of 2021, provided ‘no late tumbles or side effects’ were found by regulators. But he added that it was ‘still not yet clear’ whether the vaccine would prevent transmission of the virus - meaning a target immunisation rate could not yet be set.
Earlier in the session, MHRA chief executive Dr June Raine told MPs that more data from trials of the Oxford-/Astra Zeneca vaccine would be received ‘in the coming days’. However, she was unable to give a date for when it could be ready for roll-out.
She also told MPs that there had been two case reports of allergic reactions to the Pfizer vaccine so far, which NHS staff started to administer yesterday. The MHRA has since issued guidance warning that people with a history of significant allergic reactions should not be offered this vaccine, which is currently the only product approved for use in the UK.
Around 280 designated primary care network (PCN) sites will deliver COVID-19 vaccination from 14 December, with patients to receive a second dose of vaccine on either 4 or 5 January. Further GP-led sites will become operational in the following weeks.