Coronavirus vaccines are safe despite public hesitancy: Here are the mild side effects you could develop

Alexandra Thompson
·7 min read
Cropped hand wearing a nitrile glove holding a Covid-19 vaccine vial and a syringe
Coronavirus vaccines have long been hailed as a route out of the pandemic, however, some mistakenly worry the jabs have been rushed. The infection can cause a disease called COVID-19. (Stock, Getty Images)

Coronavirus vaccines have repeatedly been shown to be safe, however anti-vaxx sentiments appear to still linger for some.

The UK has three jabs in its immunisation arsenal, with approved vaccines being developed by Pfizer-BioNTech, the University of Oxford-AstraZeneca and Moderna.

Even people who are generally in favour of vaccinations have expressed concern the coronavirus jabs may have been rushed, despite experts previously stressing the “safety regulatory process is still there”.

Fears were further raised when the UK’s vaccine regulator stressed anyone with a “history of significant allergic reactions” should bypass the Pfizer-BioNTech jab.

This precautionary measure was issued after two NHS workers developed allergic reactions the day the vaccine was rolled out, with experts stressing flu jabs and even Marmite can cause the same side effect.

Read more: Stay motivated with social distancing as pandemic continues

Despite this repeated reassurance, a global study by the communications firm Edelman revealed just over one-third of those surveyed would be unwilling to have a vaccine within the next year, with many blaming a mistrust in governments.

In the UK, a YouGov survey found four in five (80%) are willing to have – or have already had – a coronavirus jab, making it the second most pro-vaccine country out of 24 nations.

Watch: Can you catch coronavirus twice?

Anti-vaxx sentiments are far from new. In the 18th century, Edward Jenner – “the father of immunology” – noticed milkmaids who endured the mild cowpox virus did not develop the more serious smallpox.

Similar to today’s vaccines, Jenner inserted pus from a cowpox pustule into an eight-year-old boy’s arm, leaving him immune to smallpox.

By 1820 smallpox deaths in London had significantly fallen, however, Victorians still took to the streets opposing compulsory jabs.

Fast forward to the mid-1970s, dubious research linking the whooping cough jab to brain damage reportedly caused uptake to plummet to around 30%. This led to an outbreak in 1978, with 65,000 cases and 12 children dying.

A 1981 study suggested the brain damage risk was “tiny”, around one in 310,000, yet it still took 15 years for vaccination rates to climb back to before the scare.

Read more: Nearly half ICU staff ‘meet threshold’ for severe mental health issues

Perhaps the most alarmist story was the much discredited link between the measles, mumps and rubella (MMR) vaccine and autism, published in 1998.

Former gastroenterologist Andrew Wakefield mistakenly linked the jab to autism in the journal The Lancet.

The paper has since been retracted and Wakefield struck off, with his data being called “bogus”, as well as “fatally flawed both scientifically and ethically”.

Nevertheless, vaccine fears have persisted.

Amid the coronavirus, the Edelman survey suggests just 15% of people in Russia are willing to get vaccinated as soon as possible, while only three in five (59%) in the US are eager to get a jab within a year, according to AP News.

Vaccine hesitancy appears to vary substantially around the world.

The YouGov survey found 83% would be willing to have, or have had, a coronavirus vaccine in Thailand. This is compared to less than half (47%) in the US and under a third (28%) in Poland.

Dr Edward Jenner (1749-1823) performing his first vaccination against smallpox on James Phipps, a boy of eight, May 14, 1796, oil on canvas by Ernest Board (1877-1934), 1920-1930, United Kingdom, 20th century.
Edward Jenner, the 'father of immunology', is depicted performing the first vaccination against smallpox on eight-year-old James Phipps in May 1796. (Getty Images)

How common are side effects after a coronavirus vaccine?

The Pfizer-BioNTech study that led to the vaccine’s UK approval involved more than 43,500 participants, who received either the jab or a placebo shot.

As well as the coronavirus jab warding off severe disease, the “incidence of serious adverse events was low and was similar in the vaccine and placebo groups”.

One of the most common side effects was developing mild-to-moderate pain at the injection site within a week of the vaccine, however, less than 1% endured severe discomfort.

The mild-to-moderate cases also tended to resolve within one to two days.

Read more: Why severe coronavirus causes more damage than typical pneumonia

Systemic events – like fatigue and headache – were more common among the participants aged 16 to 55, affecting 59% and 52%, respectively, after the second jab in the two-dose regimen.

The same side effects were also endured by 23% and 24%, respectively, of the same-aged placebo participants, however.

“The frequency of any severe systemic event after the first dose was 0.9% or less,” wrote the scientists.

“Severe systemic events were reported in less than 2% of vaccine recipients after either dose, except for fatigue (in 3.8%) and headache (in 2.0%) after the second dose.”

When it came to fever, “only 0.2% of vaccine recipients and 0.1% of placebo recipients reported fever [defined as a temperature of 38.9°C (102°F) to 40°C (104°F)] after the first dose, as compared with 0.8% and 0.1%, respectively, after the second dose”.

“Two participants each in the vaccine and placebo groups reported temperatures above 40°C,” wrote the scientists.

“Systemic events including fever and chills were observed within the first one to two days after vaccination and resolved shortly thereafter.”

These side effects are similar to the “very safe” flu vaccine, which can cause a slight rise in temperature, muscle aches and a sore arm.

Read more: Gut bacteria may influence severity of COVID complications

When it came to the Pfizer-BioNTech study’s more serious adverse events, 64 (0.3%) of the participants who received the vaccine and six who had the placebo (less than 0.1%) reported swollen lymph nodes.

In the vaccine group, “four related serious adverse events were reported”: shoulder injury related to vaccine administration; right axillary lymphadenopathy – abnormal lymph nodes in the right armpit; paroxysmal ventricular arrhythmia – abnormal heart rhythm; and right leg paresthesia – burning or prickling sensation.

Nevertheless, “few” participants in either group dropped out of the trial due to intolerable or dangerous side effects.

In addition, “no deaths were considered by the investigators to be related to the vaccine or placebo”, added the scientists.

UNSPECIFIED - CIRCA 1754: Gillray cartoon on vaccination against Smallpox using Cowpox serum, 1802. In 1796 the English physician Edward Jenner (1749-1823) proved efficacy of practice, but opposition continued for a while. Hand-coloured engraving (Photo by Universal History Archive/Getty Images)
Anti-vaxx sentiments are far from new. A Gillray cartoon opposed smallpox vaccines at the start of the 19th century. (Getty Images)

The University of Oxford-AstraZeneca trial is slightly more complex, in that four studies carried out in Brazil, the UK and South Africa varied in how the vaccine was administered.

Nevertheless, the scientists concluded the jab had a “good safety profile with serious adverse events and adverse events of special interest balanced across the study arms”. These arms consisted of the vaccine and control groups, where participants were given a saline or meningitis shot.

“There were 175 events, three of which were considered possibly related to either the experimental or a control vaccine,” wrote the scientists.

They previously reported how a participant endured haemolytic anaemia – when red blood cells are destroyed faster than they are made – 10 days after the meningitis jab, “considered possibly related to the intervention”.

A transverse myelitis case, inflammation of both sides of a section of the spinal cord, was reported 14 days after the coronavirus booster. The independent neurological committee later considered it to be a spontaneous event with no known cause.

Two later transverse myelitis cases were also deemed to be “unlikely” related to the vaccine.

A South African participant also endured a fever higher than 40°C two doses after a jab, but “recovered rapidly without an alternative diagnosis and was not admitted to hospital”. It is unclear if they had the coronavirus vaccine or a control shot.

Four non-coronavirus deaths occurred across the studies – a road traffic accident, “blunt force trauma”, homicide and fungal pneumonia – all of which are considered unrelated to the vaccine.

For Moderna, the most recently approved vaccine in the UK, its phase three study of more than 30,000 participants “exhibited a favourable tolerability and safety profile”.

Among the coronavirus and placebo groups, jabs were generally found to be “well tolerated”, with most side effects being “mild” or “moderate”.

The most common adverse event after both doses was injection-site pain, affecting 86% of the participants. Headache, fatigue and muscle pain were also reported by some.

“The majority of local solicited ARs [adverse reactions] occurred within the first one to two days after injection and generally persisted for a median of one to two days,” wrote the scientists.

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