Immunity from first vaccine dose could be as low as 33%
The level of immunity offered by a single dose of one of the Covid vaccines could be as low as 33%, a medical chief has warned.
Professor Anthony Harnden, deputy chair of the Joint Committee on Vaccination and Immunisation (JCVI), has said it is examining data from a study carried out in Israel which appears to suggest two doses of the Pfizer/BioNTech jab are needed before high levels of immunity can be reached.
At the end of December the JCVI, which is advising the government on the vaccine rollout, announced that the efficacy of the Pfizer vaccine was "around 90%", starting 14 days after the first dose.
They also claimed the "short term protection from dose one is very high”.
But Prof Harnden said on Sunday that the Israeli study indicates that immunity after a first dose could be as low as 33%.
"The Israeli data is preliminary data, it does involve PCR testing which is of course asymptomatic cases as well as symptomatic cases,” Prof Harnden said.
"They have not followed up for more than three weeks and the statistical methods they used are not clear."
He told Sky's Sophie Ridge On Sunday: "We will be looking at this in detail but at the moment our clear steer is the delayed second dose strategy is going to save many lives nationally."
He predicted there would be a sharp fall-off in hospitalisations and deaths a few weeks after the first four priority groups have been offered their first dose of the vaccine.
"I am confident the government has secured enough vaccine and provided the manufacturers can keep up with the orders, then we will see good supply."
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On Sunday, health secretary Matt Hancock said three quarters of all those over 80 in the UK had now been given their first jab, with a similar number of those in care homes.
But Prof Harnden warned that people could end up needing an annual coronavirus shot to keep up with variations in the virus.
“I think we have to get used to this,” he added.
"We are living in a world where coronavirus is so prevalent and rapidly mutating there are going to be new variants that pop up in all sorts of different countries."
Prof Harnden added: "We may well be in a situation where we have to have an annual coronavirus vaccine much like we do with the flu vaccine, but the public should be reassured that these technologies are relatively easy to edit and tweak, so once we find strains that are predominant, the vaccines can be altered."
"At the moment it is really good news that these vaccines we are delivering at the moment do seem to be effective against the major circulating strains and the variant strains in the UK at the moment."
