No link has been found between two Covid-19 vaccines and the number of deaths recorded after the jabs, a huge study from the United States has found.
The Centers for Disease Control and Prevention (CDC) reported that 92% of reported side effects after both the Pfizer and Moderna vaccines were mild.
Despite the fact 4,500 people died in the US after being vaccinated up to June 2021 no unusual patterns in the data were detected that might suggest a link to the vaccine itself.
Read more: Only one part of Wales now has Covid patients in intensive care
Study author Dr Tom Shimabukuro told the BBC : "[It's] reassuring that reactions to both mRNA vaccines are generally mild and subside after one or two days – confirming reports from clinical trials and post-authorisation monitoring."
Researchers looked at "adverse events" from nearly 300m vaccine doses given in the US between December 2020 and June 2021.
Members of the public, healthcare providers and drug companies can report any possible side effect using the Vaccine Adverse Event Reporting System (VAERS) run by the CDC and the US Food and Drug Administration (FDA). A second method, called V-safe, allows people to fill out a survey on their smartphone in the months after after vaccination. Both systems rely on individuals deciding to self-report an adverse event. The results of the study are published in the Lancet medical journal.
From the VAERS data the CDC received more than 340,000 reports of adverse events after vaccination with 92% registered as mild. The most common side effects were headaches, fatigue, fever, and chills. Of the more than 22,000 events recorded as serious the most common was shortness of breath.
Other serious events, including a form of heart inflammation known as myocarditis, have already been identified following both the Pfizer and Moderna vaccinations although that side effect is very rare.
Because Covid jabs were originally authorised in the US under emergency-use provisions healthcare providers are required to report all deaths following vaccination whether a doctor suspects a "plausible" link or not.
About 4,500 deaths were recorded in the six months to June 2021 with more than 80% among people aged 60 and over.
"The rapid pace at which Covid-19 vaccines were administered under emergency use, especially among older populations, was unprecedented," the CDC's Dr David Shay said.
"Due to their age this group already has a higher baseline mortality rate than the general population and our results follow similar patterns of death rates for people in this age group following other adult vaccinations."
The researchers said less than 1% of people who filled out the V-safe survey had sought any medical care following vaccination.
Dr Elizabeth Phillips, professor of medicine at Vanderbilt University and who was not involved in the study, told the BBC: "Reassuringly the six-month VAERS data supports that – although approximately one in 1,000 individuals vaccinated may have an adverse effect most of these are non-serious.
"For adverse events of special interest it is reassuring that there were no unexpected [safety] signals other than myocarditis and anaphylaxis, already known to be associated with mRNA vaccines."
In Wales almost 6.9m doses of the coronavirus vaccine have been delivered since the programme was launched just over a year ago.
According to Public Health Wales, 2,521,885 people have now received one dose of the coronavirus vaccine and 2,389,355 have been given two doses. Meanwhile 1,912,811 people have been given their booster jabs.
Older people, along with the most vulnerable, will be offered a spring booster vaccine to "top up" their protection.
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