Leading experts have warned delaying the second dose could have a “catastrophic” impact on the efforts to end the coronavirus crisis. They fear the delays to the second jab could foster vaccine-resistant mutations in the virus, making it harder to end the pandemic. In December the Government announced the second dose would be given towards the end of 12 weeks rather than in the previously recommended 3-4 weeks.
They said they want to give a single dose of the jab to as many members of priority groups as possible.
The World Health Organization’s expert scientific advisors have said they do not recommend that other countries follow the British approach, but they also says it understands why the UK has chosen to go down this road.
Professor Herb Sewell, emeritus professor of immunology and consultant immunologist at Nottingham University, said abandoning the recommended 21-day gap was “madness”.
He told the Sunday Times: “Even if the risk is small, the potential consequences are catastrophic. For example, a mutation that is not treated by the current vaccines impacting the population — the UK and the wider world.”
Professor Paul Bieniasz, a virologist at Rockefeller University in New York, also warned delaying the jab could have unintended consequences and had the potential to create “a large population of susceptible hosts with partial immunity”.
He said this could see people waiting for a second dose get infected and fend off the virus more slowly.
The danger was that people might avoid serious illness, but the virus would have time to mutate to evade their antibodies.
This new vaccine-resistant strain could then wreak havoc and make it difficult for the pandemic to ease.
In December, the UK’s Joint Committee on Vaccination and Immunisation (JCVI) said: “Given data indicating high efficacy from the first dose of both Pfizer-BioNTech and AstraZeneca vaccines, the committee advises that delivery of the first dose to as many eligible individuals as possible should be initially prioritised over delivery of a second vaccine dose.
“This should maximise the short-term impact of the programme.
“The second dose of the Pfizer-BioNTech vaccine may be given between three to 12 weeks following the first dose.
“The second dose of the AstraZeneca vaccine may be given between four to 12 weeks following the first dose.”
The four UK chief medical officers agreed to follow the JCVI advice, as they believe the benefit of vaccinating more people outweighs the risk of individuals not having as strong a protection against infection as they might have with two doses.
Experts have questioned whether the vaccine will still be effective if the second dose is delayed.
Pfizer, the company behind the first jab approved by the UK, put out a statement saying there was no evidence from its trials to suggest efficacy levels remain the same.
They said: “There are no data to demonstrate that protection after the first dose is sustained after 21 days.”
Pfizer’s phase 3 final trial showed people began to be protected from 12 days after one vaccination – but nearly all were given two shots within three weeks.
More to follow…