Covid vaccines offer better protection than natural immunity, researchers claimed today.
The true extent of immunity to the coronavirus remains shrouded in mystery.
Some research has suggested that getting infected naturally offers more protection than any vaccine.
But Britain’s largest coronavirus symptom tracking app now favors jabs.
Experts from King’s College London and health technology company ZOE, who run the software, say a natural infection on its own prevents 65 percent of people from contracting the virus again.
But two doses of AstraZeneca were found to be slightly better, with an efficacy of about 71 percent. Pfizer’s was even stronger: the double-dose course offered about 80 percent protection after six months.
Professor Tim Spector, the lead scientist behind the app, said: ‘Regardless of which vaccine is administered, this research shows that natural Covid infection before double vaccination means more protection.’
Despite the findings, the study also suggested that natural immunity does not begin to wane until at least a year, but vaccine protection can begin to weaken after as little as three months.
But experts said other research suggests natural infection offers similar protection to the Pfizer jab but is “more effective than AstraZeneca.”
The data from ZOE shows that two doses of AstraZeneca (71 percent) or Pfizer (80 percent) – the vaccines most commonly used in the UK – are more effective at preventing infection within six months than a previous infection. Natural infection offered only 65 percent protection. But those who caught Covid and then got a double shot with AstraZeneca (90 percent) or Pfizer (94 percent) had the strongest defenses against contracting the virus
Experts have previously argued that natural infection is the best form of defense against the virus, especially in young people who receive only one dose.
This has fueled arguments against vaccinating children, who are at much lower risk of becoming seriously unwell from the virus and more likely to experience a very rare side effect of heart inflammation called myocarditis.
However, it is difficult to determine which option offers the best protection.
Covid efficacy against Pfizer infection drops to 20% after six months – but protection against serious illness barely drops, real world data from Qatar shows
Pfizer’s Covid shot is only 20 percent effective at preventing people from becoming infected after six months, real world data shows.
Two doses of the vaccine prevent 80 percent of people from contracting the coronavirus after a month, Qatari researchers said.
The findings – based on an analysis of nearly a million people – reflect efficacy estimates pumped out by UK health chiefs.
But the study showed that protection gradually declined, to just 22.3 percent after six months among fully vaccinated people.
Still, scientists maintain that protection against serious illness and death remains high after six months, at around 90 percent.
Amid fears that vaccine-induced immunity will wane after a few months, UK ministers have embarked on a booster drive. About 30 million over-50s and NHS workers will be eligible for a third dose six months after their second.
British health chiefs insisted that protections against serious illness remain high.
But they chose to continue to roll out boosters to keep the immunity levels of the most vulnerable in winter high.
Qatar launched its vaccine rollout program last December using the Pfizer vaccine – doses spaced three weeks apart. Then in March it started handing out Moderna’s similar jab.
While it is known whether someone has received a vaccine, millions of people have had Covid without being tested, making it difficult to calculate protection accurately.
One study showed that natural immunity could provide 13 times more protection against infection than two doses of Pfizer’s vaccine.
The ZOE team noted that the vaccine’s effectiveness doesn’t necessarily decline after six months, but they have no data beyond this time frame.
But those who caught Covid and then got a double shot with AstraZeneca (90 percent) or Pfizer (94 percent) had the strongest defenses against contracting the virus.
The researchers did not compare the protection of one dose of each vaccine with a natural infection.
The findings, based on real-world data from more than a million vaccinated Britons and test results between May and July, also showed that the immune response to an infection lasts for up to 15 months.
In the meantime, vaccine protection begins to wane after three months, according to ZOE data.
The researchers said this means that people who contracted Covid and were subsequently vaccinated “are likely to maintain a higher level of protection against Covid for longer than those who were not infected” before vaccination.
Professor Spector added: ‘This is really positive news for overall immunity levels in the UK and means that large numbers of people will have effective and long-lasting protection against Covid.
“This is also strong evidence to support the need for vaccination, even for those who have already had Covid.”
Professor Paul Hunter, an expert in medicine at the University of East Anglia, told MailOnline the data is “valuable confirmation” of studies that have already shown infection increases vaccine protection.
He said, “You can think of a natural infection as a booster vaccination.”
As the virus becomes endemic, people are likely to be repeatedly infected every few years, he said.
Professor Hunter said that “the latest evidence for Delta suggests that natural infection is about as effective as Pfizer, but more effective than Astrazeneca.”
Dr Alexander Edwards, an immunologist at the University of Reading, told MailOnline: ‘It’s really surprising, but we find it a lot more difficult to determine how much protection is provided by natural infection than by vaccines.
‘On the one hand, our immune system is just brilliant at responding to many different infections.
“However, viruses and bacteria have tricks that allow them to evade immunity – Covid is no different.
‘The vaccines, on the other hand, are designed purely to promote potent immunity directly against the main viral target – the peak on the outside – so we are very pleased, but perhaps not surprised, that they offer such excellent protection.
“The way the vaccines work creates a powerful antibody response to that exact target.
‘We can measure these antibodies and are usually higher after vaccination than after infection, so we expect the vaccines to offer better protection than natural infection, because these ‘virus neutralizing antibodies’ are so important.
“What they’re doing is binding and removing the virus so it can’t enter our cells — so overall, the observations from the Zoe study are a great relief to immunologists, confirming what we’d hoped for.”