No data to support delay of second Covid vaccine dose, say Pfizer and BioNTech

UK vaccine strategy continuing to spark fierce scientific debate

BioNTech and Pfizer have warned against delaying the provision of a second dose of their vaccine, after the UK government adopted the strategy in an attempt to make the country’s supplies go further.

Amid an escalation in Covid-19 cases across the four nations – driven in part by the new coronavirus variant – government health officials heeded calls to roll out initial supplies of the vaccines to as many people as possible, rather than holding back jabs to give second doses to those who have received the first.

The Oxford-AstraZeneca and Pfizer-BioNTech vaccines will now be administered in two doses up to three months apart, rather than over a four-week or three-week period, allowing more people to be inoculated in a shorter time frame.

However, BioNTech and Pfizer said there is no evidence that their candidate will continue to protect against Covid-19 if the booster shot is given later than tested in trials.

"The safety and efficacy of the vaccine has not been evaluated on different dosing schedules as the majority of trial participants received the second dose within the window specified in the study design," the companies said in a joint statement, referring to prime and a booster shots given three weeks apart.

"There is no data to demonstrate that protection after the first dose is sustained after 21 days.”

Denmark has approved a delay of up to six weeks between the administration of the first and second shots of the vaccine.

Germany is also considering whether to implement the strategy, amid criticism that the health officials have failed to procure enough supplies of the vaccine and been unable to accelerate its nationwide inoculation campaign.

Leif Erik Sander, head of the vaccine research team at Berlin’s Charité hospital, said: “In view of the current scarcity of vaccines and the very high numbers of infections and hospitalisations in Germany, a strategy in which as many people as possible are vaccinated as early as possible is more effective.”

Professor Jonathan Van-Tam, England’s deputy chief medical officer, has thrown his support behind the strategy, saying the UK is caught in “a race against time” to bring the virus under control.

“Simply put, every time we vaccinate someone a second time, we are not vaccinating someone else for the first time,” he told the Daily Mail. “It means we are missing an opportunity to greatly reduce the chances of the most vulnerable people getting severely ill from Covid-19.”

The Joint Committee on Vaccination and Immunisation (JCVI) has found the Pfizer vaccine to be 89 per cent effective against Covid-19 from between 15 and 21 days after the first dose, according to Prof Van-Tam. That rises to 95 per cent after the administration of the booster jab.

“If a family has two elderly grandparents and there are two vaccines available, it is better to give both 89 per cent protection than to give one 95 per cent protection with two quick doses, and the other grandparent no protection at all. The virus is unfortunately spreading fast, and this is a race against time,” he said.

“My mum, as well as you or your older loved ones, may be affected by this decision, but it is still the right thing to do for the nation as a whole.”

According to research from the London School of Hygiene and Tropical Medicine, the UK must vaccinate at least two million people a week in order to prevent a third wave.

Without strict coronavirus prevention measures and a “substantial vaccine rollout”, the pandemic’s impact on Britain could be worse in 2021 than in 2020, the study added.

Independent Sage said there was “sound theoretical and empirical public health reasons” to support the decision to delay a second dose of the Oxford vaccine, including trial evidence which showed this prolonged interval boosts its effectiveness in preventing Covid disease.

But the US Food and Drug Administration (FDA) has warned that changing the authorised dosing or schedules of Covid-19 vaccines is premature and not supported by the available data.

The American regulator said it had been following discussions and news reports about reducing the number of doses, extending the length of time between doses, cutting the dosage in half, or mixing and matching vaccines in order to immunise more people.

Although these were "reasonable" questions to consider, it said, "at this time suggesting changes to the FDA-authorised dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence".

"Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk," the FDA said in a statement on Monday.