Covid vaccine protection waning in double jabbed

Researchers are seeing some waning of protection against Covid infections in people who are double-jabbed with a vaccine.

The study looks at data from over a million people with positive Covid PCR test results between May and July 2021 who have received two doses of Pfizer or AstraZeneca vaccine.

After two doses of Pfizer, protection drops from 88% at one month to 74% at five to six months. While AstraZeneca falls from 77% to 67% at four to five months.

However, experts say they expect some waning in protection. But even though there is some breakthrough in infections, vaccines are still doing a good job at protecting people against serious illness and death.

Saving lives

Public Health England estimates that the Covid vaccination programme has prevented about 84,600 deaths and 23 million infections so far in England.

The lead investigator behind the research, Professor Tim Spector, says the findings could explain recent reports of infections in some fully vaccinated people. But he reiterates that waning is expected and is not a reason to refuse vaccination. He says, “vaccines still provide high levels of protection for the majority of the population, especially against the Delta variant, so we still need as many people as possible to get fully vaccinated”.

Professor Spector predicts that by the winter protection against infection could fall to 50% and people will need boosters. But other experts are more wary about making predictions for the future.

A third Covid booster jab is expected to start for some people in the UK next month. But this is still awaiting recommendation from independent advisory body the JCVI. They are looking at evidence to support the decision.

However, Professor Spector believes that many people may not need a booster jab. He thinks they might have a natural booster due to having had a Covid infection. Having the virus builds up a natural immunity which effectively acts as another vaccine. This is why the process needs carefully managing and a more targeted approach. Just giving a third vaccine to everybody is a big waste of resources.

Imperfect protection

Meanwhile, Dr Simon Clarke, an expert in cellular microbiology at the University of Reading, says virus levels in the community change a person’s risk of catching coronavirus. This makes it difficult to form solid conclusions about waning immunity.

Fellow at the University of Reading, Dr Alexander Edwards, agrees it is important to understand when and for whom booster doses may be required. He says vaccination does not “make people invulnerable, and does not prevent all infections”. Variants have a significant impact on health, and many are “still tragically dying in the UK from this nasty virus”. But there are still “massive benefits” to vaccination. Our vaccines “are remarkably safe and effective, and still remain far better” than others. He adds that we need a pro-active plan for our public health strategy to “account for imperfect protection, and for the possibility of falling protection over time”.

Last week, the Office for National Statistics and the Oxford Vaccine Group published a similar study based on PCR test results from around 400,000 UK people who had the Delta variant. It found that at first, two doses of Pfizer vaccine is over 90% effective against symptomatic Covid infection. This compares to about 70% for the AstraZeneca vaccine. However, protection from Pfizer dropped significantly over three months, while AstraZeneca stayed more stable.

Government vaccine adviser Professor Adam Finn says other studies show the vaccines remain good at protecting against severe illness and hospitalisation. But he warns we need to keep a close eye on things. If waning against mild disease turns to more occurrences of serious cases then booster jabs may become necessary.

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