Covid survivors are almost twice as likely to suffer side effects from Pfizer’s vaccine compared to those who have never contracted the virus, data suggests. 

Figures from a symptom-tracking app show 33 per cent of people who had already been struck down the virus endured at least one mild side effect — such as fatigue or a headache a week after getting their jab.

For comparison, the rate was just 19 per cent among non-Covid sufferers. 

The ZOE Covid-19 Symptom Study app revealed the most common side effect was fatigue, with nine per cent. It was followed by headaches (eight per cent) and chills (four per cent). 

Meanwhile, the data also showed most of the side effects — known as systematic because the whole body is affected — appeared within 48 hours of getting vaccinated.

Only three per cent experienced complications lasting beyond three days. 

The ZOE Covid-19 Symptom Study app revealed that 33 per cent who had previously contracted the virus experienced one or more mild side effects after seven days compared to 19 per cent of non-Covid sufferers

Covid survivors are almost twice as likely to suffer side effects from Pfizer ‘s vaccine compared to those who have never contracted the virus, data suggests

Professor Tim Spector, an epidemiologist at King’s College London who heads up the ZOE Symptom app which also estimates infections throughout the country, said that the data suggests that the first dose for those who have previously had Covid behaves like a booster jab.    

The study analysed data from people of all ages who had 40,000 doses between them. 

It found 37 per cent had pain or swelling near the site of the jab after the first dose, which increased to 45 per cent after the second dose. 

Data also showed 14 per cent of participants reported at least one side effect within seven days following the first dose, compared to 22 per cent after the second jab —suggesting the top-up dose causes a stronger immune response.   

The figures showed 13 per cent of men logged at least one side effect within seven days, compared to 19 per cent of women who had received the vaccine.  

The under-55s were more likely to experience a side effect, with 21 per cent logging at least one symptom compared to 14 per cent of over-55s.    

Commenting on the effects after the Pfizer/BioNTech vaccination, he said: ‘It is really suggesting that if you have had Covid before your first vaccine it is behaving a bit like the second one — like a booster. 

He described how the higher rate of side effects seen in people who had previously Covid suggests that: ‘People already had an immune response and they are getting an even bigger booster so that their immunity is going to be stronger.’ 

Professor Spector added: ‘I am expecting once we analyse and get a bit more of the data we are going to show that this group who previously had Covid, maybe six months before, have an even bigger protection, even bigger than the 53 per cent after that single dose.


So far the UK has placed orders for 367million doses of the seven most promising Covid vaccines — made by AstraZeneca , Pfizer , Moderna, Valneva, Janssen, GlaxoSmithKline and Novavax — at a cost of £2.9billion

Pfizer/BioNTech’s breakthrough jab was the first in the world to be proven to successfully block severe Covid-19 last year and it gained approval in the UK on December 2

Covid survivors may only need one vaccine dose because they already have antibodies

People previously infected with coronavirus may only need one dose of the vaccine, a new study suggests.

Researchers found that participants who had contracted COVID-19 in the past and received one shot had antibody levels similar to – and even higher than – those who had never been infected and were given two doses.

Additionally, virus survivors were more likely to report side effects after being immunized such as pain at the injection site, fever and fatigue.

The team, from the Icahn School of Medicine at Mount Sinai in New York, says giving previously infected individuals only one dose would ‘spare them from unnecessary pain and free up many urgently needed vaccine doses.’

‘I think it invites the question about whether with a bit more data we might be able to say that these people don’t need a second booster and that really they have already had their first one which is the Covid and the second one which is the first vaccination. 

‘That would potentially save around 10million vaccines or at least it could be delayed maybe several months more.’ 

The breakthrough jab was the first in the world to be proven to successfully block severe Covid-19 last year and it gained approval in the UK on December 2. 

It uses brand-new technology and is known as a messenger RNA (mRNA) vaccine. Conventional vaccines are produced using weakened forms of the virus, but mRNAs use only the virus’s genetic code.

An mRNA vaccine is injected into the body where it enters cells and tells them to create antigens. These antigens are recognised by the immune system and prepare it to fight coronavirus.

Studies showed the two-dose vaccine could prevent severe illness in 95 per cent of people who were injected with it. 

The Government has ordered 40million doses, enough to vaccinate 20million Brits, but only a handful of million Brits have received the jab so far.

Having vaccines on order is not the same as having them ready to go. Manufacturers are still trying to ramp up production to deliver the agreed supplies around the world.   

The UK ran into some logistical difficulties when trying to roll the vaccine out last year which stalled how quickly it could be deployed.

The downside to mRNA vaccines is that they need to be stored at ultra-cold temperatures and cannot be transported easily. 


Moderna and Pfizer/BioNTech have both released interim results of the final stage clinical trials of their vaccines, with both suggesting they are extremely effective. 

Oxford University has published the findings from its second phase, which show the jab provokes an immune response and is safe to use – it is not yet clear how well it protects against coronavirus in the real world.

Here’s how they compare: 


mRNA vaccine – Genetic material from coronavirus is injected to trick immune system into making ‘spike’ proteins and learning how to attack them.

mRNA vaccine – both Moderna’s and Pfizer and BioNTech’s vaccines work in the same way.

Recombinant viral vector vaccine – a harmless cold virus taken from chimpanzees was edited to produce the ‘spike’ proteins and look like the coronavirus.

94.5% effective (90 positive in placebo group, 5 positive in vaccine group) .

95% effective (160 positive in placebo group, 8 positive in vaccine group).

62% – 90% effective, depending on dosing.

Moderna confirmed it will charge countries placing smaller orders, such as the UK’s five million doses, between £24 and £28 per dose. US has secured 100million doses for $1.525billion (£1.16bn), suggesting it will cost $15.25 (£11.57) per dose.

The US will pay $1.95bn (£1.48bn) for the first 100m doses, a cost of $19.50 (£14.80) per dose.

Expected to cost £2.23 per dose. The UK’s full 100m dose supply could amount to just £223million.

UK has ordered five million doses which will become available from March 2021. Moderna will produce 20m doses this year, expected to stay in the US. 

UK has already ordered 40million doses, of which 10million could be available in 2020. First vaccinations expected in December.

UK has already ordered 100million doses and is expected to be first in line to get it once approved.

What side effects does it cause? 

Moderna said the vaccine is ‘generally safe and well tolerated’. Most side effects were mild or moderate but included pain, fatigue and headache, which were ‘generally’ short-lived. 

Pfizer and BioNTech did not produce a breakdown of side effects but said the Data Monitoring Committee ‘has not reported any serious safety concerns’.

Oxford said there have been no serious safety concerns. Mild side effects have been relatively common in small trials, with many participants reporting that their arm hurt after the jab and they later suffered a headache, exhaustion or muscle pain. More data is being collected.

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