Pfizer, AstraZeneca Covid vaccine protection wanes within six months, study finds

Protection against Covid-19 offered by two doses of the Pfizer/BioNTech and the Oxford/AstraZeneca coronavirus vaccines begins to fade within six months, underscoring the need for booster shots, according to researchers in Britain.

The efficacy of the Pfizer jab at preventing Covid-19 infection fell from 88 per cent in the month after the second dose to 74 per cent after five to six months, an analysis of data collected in Britain's Zoe Covid study showed.

For the AstraZeneca vaccine, efficacy fell from 77 per cent to 67 cent after four to five months. The study was based on data from more than 1.2 million test results.

Previous analysis has suggested vaccines provide protection for at least six months.

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Under a worst-case scenario, protection could fall below 50 per cent for older people and healthcare workers by the winter, Tim Spector, principal investigator for the Zoe Covid study, said.

“It’s bringing into focus this need for some action. We can’t just sit by and see the protectiveness slowly waning whilst cases are still high and the chance of infection still high as well,” Mr Spector told BBC television.

Minster for Health Stephen Donnelly has said the National Immunisation Advisory Committee (Niac) met on Monday to consider new data on vaccine efficacy and that he expected a recommendation from them this week on a vaccine booster campaign.

He said such additional vaccine shots could start to be administered this autumn and winter once Niac identifies which population groups should be prioritised.

Britain is starting to plan for a Covid-19 vaccine booster campaign later this year after senior vaccine advisers said it might be necessary to give third shots to the elderly and most vulnerable from September.

Nursing Homes Ireland (NHI) chief executive Tadhg Daly called for the Government to expedite the rollout of the booster vaccines to nursing home residents, saying that the latest research on Covid-19 vaccine protection offered a "very serious warning to our health services". He also underlined that research showed the waning of vaccine immunity would start among nursing home residents, "who are most susceptible to the virus".

Mr Daly added that there had been a “small but concerning rise” in the number of Covid-19 outbreaks in nursing homes, with the expected peak still anticipated in the weeks ahead.

WHO call

Meanwhile, the World Health Organisation (WHO) has called for a halt on Covid-19 vaccine boosters until at least the end of September as the gap between vaccinations in wealthy and poor countries widens.

Executive director of the WHO's emergencies programme Mike Ryan underlined last week that millions of people were being left without any protection against the disease while wealthy countries were preparing to hand out third doses. Dr Ryan said giving Covid-19 booster shots to people already fully vaccinated against the disease was like handing out extra life jackets to some while leaving others to drown.

Speaking on the RTÉ Today show on Wednesday, WHO spokeswoman Dr Margaret Harris called on Ireland "not to rush and corner all the supplies of vaccines, something we've been struggling with all year.

“It’s because we are still trying to get them out to the most vulnerable people in the world, healthcare workers, the elderly, many of those people in many countries have not even had their first jab.”

Ensuring the initial two-dose vaccination of as many people worldwide as possible is needed “in order to protect all of us from the development of further variants and further outbreaks”, said Dr Harris. “We won’t win this unless we stick together.”

She added that all vaccines were resulting in very good protection against the two most critical outcomes of the virus – death and severe disease. However, they are not preventing transmission which risks leading to more variants, she said.

She acknowledged that some vaccines were losing their efficacy in preventing milder disease but that the focus must be on dealing with the “big things first”.

“We also do recognise there are people who will need extra doses, there are people whose immune systems aren’t that strong in the first place and those people are in a different category and those people should certainly get further vaccine support.

“We really do need to get a bit better at looking after everyone in the world, not just because we want to be better people, but we also want to be people that beat this virus.”– Additional reporting Reuters