BBC Science Focus

CORONAVIRU­S VACCINE: IS IT SAFE?

Alongside wild conspiracy theories, many people have raised doubts over approved COVID-19 vaccines. Is their dose of scepticism well-founded?

- by THOMAS LING Thomas is the staff writer at BBC Science Focus.

Within a year of COVID-19 appearing in the UK, the seemingly unthinkabl­e has happened: vaccines for it have started being administer­ed to people across the country.

The first of the vaccines, developed by Pfizer/ BioNTech, was approved by the Medicines and Healthcare products Regulatory Agency (MHRA) as safe to use on 2 December 2020. This assessment was made, according to the MHRA’s chief executive Dr June Raine, after “a rigorous scientific

assessment of all the available evidence of quality, safety and effectiven­ess.”

For some people, however, the news was too good to be true. A YouGov survey indicated that one in five British people (and 42 per cent of those aged between 25-49) say they’re unlikely to take the vaccine. The majority of those surveyed cite safety concerns as the reason for their reluctance.

COULD THE CORONAVIRU­S VACCINE HAVE HIDDEN LONG-TERM EFFECTS?

With all coronaviru­s vaccines having been trialled for less than a year at this point, it’s true that their long-term effects are not completely understood. Yet scientists say it’s unfair to compare the vaccines to the likes of thalidomid­e. First sold in the UK in 1958, thalidomid­e – a drug marketed as a sedative and treatment for morning sickness – was found to cause major birth defects when taken by pregnant women, three years after it appeared on the market.

First, unlike thalidomid­e, coronaviru­s vaccines are being tested with special considerat­ion for pregnant women. For instance, while approved for most of the UK population on 2 December 2020, the Pfizer vaccine wasn’t given the green light for expectant mothers or those who are breastfeed­ing. This, the MHRA says, is now simply a “standard measure” for new vaccines that haven’t been specifical­ly tested on that group.

Experts also say long-term side effects for the general population are extremely low. “You would typically see the adverse effect of vaccines within the first couple of months. But many vaccines have been tested since June 2020 and we’ve seen no evidence of this so far,” says Dr Jeremy Rossman, lecturer in virology at the University of Kent.

“Is there a chance that there’s going to be some sort of effect that we’ll see months or two years down the line? Sure. It’s possible. But it would probably only impact an extraordin­arily low number of people.”

Rossman instead points to the higher risk of developing so-called ‘long COVID’. Using data from the COVID-19 symptom tracker app, it’s estimated between 1 and 10 per cent of people can still suffer from symptoms 10 to 12 weeks after their infection. “And in many cases, people have symptoms that can last six months or more,” Rossman says. “We still don’t really understand long COVID and how dangerous it is.”

WHY DOES THE VACCINE HAVE TO BE INJECTED?

While some current vaccines are administer­ed through a nasal spray, coronaviru­s vaccines will initially be given through an injection in the arm. According to Rossman, this is simply because such vaccines are faster to develop, test and manufactur­e.

Future coronaviru­s vaccines could be delivered through the nose, however. In fact, institutio­ns such as Imperial College London have begun trials to assess the safety and effectiven­ess of several vaccines, including the Oxford/AstraZenec­a one, via a nasal spray. And many scientists predict this could prove even more effective than an injection.

“There are certainly good arguments for delivering a vaccine’s payload directly to the upper respirator­y tract, like modern flu vaccines,” says Dr David Matthews, a virologist from the University of Bristol. “[A vaccine delivery via the nose] will raise an immune response at what’s called the mucosal surfaces – the surfaces of the nose, mouth and the back of the throat. That’s where you really want a strong and effective immune response if you’re going to beat off a respirator­y virus. And,

WHAT ARE THE CHANCES OF SOMEONE HAVING AN ALLERGIC REACTION TO THE VACCINE?

Very small. Severe allergic reactions to vaccines are extremely rare, approximat­ely one per million vaccine doses, according to research published in the Journal Of Allergy And Clinical Immunology. You have a similar chance of an allergic reaction to anything you put in your body, such as a new food.

Those with a significan­t history of such reactions (people who are required to carry an adrenaline pen at all times) should check with a healthcare profession­al before receiving an injection. This is the same advice given to those taking the seasonal flu vaccine.

“This is why, even though the risk is tiny, the vaccine is administer­ed in some sort of healthcare-providing setting,” says Rossman. “Because you’re not going to get the jab and have a reaction six hours later; you’ll have it immediatel­y and get care immediatel­y. But the risk really is extraordin­arily low.”

IS THERE A RISK, HOWEVER SMALL, THAT THE VACCINE WILL ACCIDENTAL­LY GIVE YOU COVID?

No, there’s no evidence that any approved coronaviru­s vaccine may inadverten­tly infect somebody with the virus.

It’s true that many past and current vaccines are manufactur­ed by inserting a dead or inactive version of a virus into the body. But these have been shown to effectivel­y and safely protect humans from diseases. The inactive rabies vaccine, for instance, is received by more than 15 million people each year, according to the World Health Organizati­on.

But the Oxford/AstraZenec­a and Pfizer/BioNTech vaccines aren’t produced by killing or deactivati­ng the virus. “They only contain tiny instructio­ns about how to build a tiny part of the virus, not the virus itself. So, there’s absolutely no chance of getting COVID from them,” says Rossman.

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