COVID-19 vaccines

Last modified

May 18, 2022 @ 14:57 PM

The first vaccines against COVID-19 were approved in December 2020. Further COVID-19 vaccines have since been approved and many others are in development

As COVID-19 is a relatively new disease, and the first COVID-19 vaccines were introduced in late 2020, you may have some questions you would like answered prior to having the vaccine. 

A number of agencies and health authorities – including the European Medicines Agency, the World Health Organization, the Children’s Hospital of Philadelphia, the British Society for Immunology, and Immunise BC – have developed answers to frequently asked questions about COVID-19 vaccines. 

Here, we summarise some of the most common issues raised, along with comments we’ve picked up from our social media channels. If there is a question you would like us to add, contact us. We focus below on vaccine development and technologies, as well as safety and efficacy. For information about vaccine delivery in your area, contact local health authorities. 

How were COVID-19 vaccines developed within one year?

It usually takes several years to develop a vaccine. The successful development of COVID-19 vaccines is down to foresight, hard work and good luck. Given the urgency of containing a global pandemic, unprecedented resources were directed at vaccine development. 

Crucially, clinical trials were streamlined without compromising on safety. Tens of thousands of people volunteered to take part in trials; phases of trials were overlapped rather than being conducted consecutively; and regulators began ‘rolling reviews’ while trials were ongoing. 

At the same time, even before vaccines were independently approved by regulators, governments placed advance orders for vaccines and companies began manufacturing. This meant that when regulators were satisfied that vaccines were safe and effective, millions of doses could be shipped around the world. 

Do COVID-19 vaccines work?

Yes. In clinical trials, the vaccines now approved for use have been shown to prevent COVID-19 in most people. Precise results from clinical trials vary from vaccine to vaccine, but published data indicate a strong reduction in severe disease, hospitalisation and death among people who have been vaccinated.

Are COVID-19 vaccines safe?

The short answer is ‘Yes’. COVID-19 vaccines have been approved by independent regulators following clinical trials on tens of thousands of people. Since their authorisation, billions of people have had COVID-19 vaccines. 

The most common side effects of approved COVID-19 vaccines are fatigue, headache and muscle aches. These local effects are short-lived and are expected. In a small number of individuals, allergic reactions have been recorded. For some vaccines, very small numbers of people have experienced blood clotting abnormalities or information of heart muscle. Speak to your health professional if you have a history of allergic reactions or concerns about any of these issues.

What about long-term effects?

As COVID-19 is a new disease, and COVID-19 vaccines are new, it is not scientifically possible to know the long-term impact of the disease or the vaccines. However, 12 billion doses have now been administered worldwide. In Europe, many older people had their first dose in December 2020; millions of these have now had their fourth COVID-19 vaccine dose.

How many doses do I need?

Most of the COVID-19 vaccines currently available were initially approved for a two-dose regimen. A single-dose vaccine is also approved and may be available. Data from trials suggests that a strong response is generally seen 7-10 days after the first dose in most people. The typical gap between these initial two doses is three to four weeks. Your health professional/health authorities will advise on when you should return for a second dose. 

If you have had two doses of COVID-19 vaccine, you may have been called for a booster or third dose. This is recommended where protection is likely to have waned. In some European countries, older people and those at risk of serious complications due to problems with their immune system have been offered a fourth dose.

Will the vaccine prevent transmission of the disease?

In short, we don’t know precisely how well vaccines affect transmission. It appears that vaccines have some impact on whether individuals can spread the virus. However, it is also clear that many vaccinated people have contracted and passed on the virus. And, as the first generation of vaccines were designed for the original strain of SARS-CoV-2, new variants may evade or partially evade the protection offered by vaccination. The clinical trials for approved COVID-19 vaccines tested whether vaccines prevented disease (which they did). For a more detailed look at the science behind this question, try here.

What are mRNA vaccines?

Some of the earliest vaccines approved for use against COVID-19 use mRNA technology. These vaccines contain a short piece of messenger RNA (mRNA) – a string of genetic instructions. Like a recipe, these instructions tell the body to make a specific, single protein from the virus (and not the whole virus). This ‘spike protein’ is on the surface of the SARS-CoV-2 virus, and is the part of the body that our immune system needs to learn to recognise. These are the characteristic spikes that you may have seen in images showing the surface of the virus. 

When the body has made these proteins, the immune system destroys them and remembers them if the virus enters the body in future, like what happens in natural infection against COVID-19. The mRNA from the vaccine breaks down quickly and disappears .

What are the other types of vaccines that have been approved?

Whereas mRNA vaccines deliver mRNA for the spike protein wrapped up in tiny parcels of ‘fat’, other vaccines use a slightly different approach to achieve the same result. A vaccine developed at Oxford University, available across Europe, delivers the genetic code for the SARS-CoV-2 spike protein to the body by inserting it into another virus. This virus cannot replicate, making it harmless. Once inside the body, it triggers an immune response. 

Another type of vaccine, known as a ‘protein subunit vaccine’, has been approved by regulators in the EU, the UK, the US and elsewhere. This type of vaccine contains harmless and purified pieces of the virus trigger immunity. This approach to making vaccines has already been used for several other diseases including flu, pertussis, hepatitis B and meningococcal disease.

Who are COVID-19 vaccines for?

Available COVID-19 vaccines have been tested on adults, adolescents and children. The first trials were conducted in adults with later tests on children which were approved by regulators.

What about children?

While many vaccine-preventable diseases affect children, it appears young people are at the lowest risk of being severely affected by COVID-19. However, children can suffer significant short-term illness, with some developing longer health issues follow infection with SARS-CoV-2.

Including children in vaccine trials is not unusual. Children are usually included in clinical trials for RSV or meningitis vaccines, for example. For COVID-19, the first priority when the pandemic began was to protect adults. The earliest trials focused on adults of all ages and vaccines were approved on that basis, with trials in adolescents and children beginning several months later.

In the summer of 2021, vaccines were approved by regulators for adolescents (aged 11-16). Subsequently, based on strong data from clinical trials in children, the European Medicines Agency (EMA) has approved COVID-19 vaccines for children aged 5-11. Children are offered one third of the dose given to adolescents. This dose provides a level of protection similar to that seen in teenagers and young adults who are given the higher dose which is approved for that age cohort.

Can pregnant women have COVID-19 vaccines?

Pregnant women were not recruited for initial trials on COVID-19 vaccines. As a result, vaccines were initially not recommended during pregnancy, except where the individual is at high risk of COVID-19.

Over time, data has been collected on the safety of vaccinating women who did not know they were pregnant at the time of vaccination. This helped to provide a fuller picture of the safety of COVID-19 vaccines during pregnancy. Information on the risk to pregnant women and their babies has also been studied closely. As a result women who are pregnant are strongly advised to have a COVID-19 vaccine.

The European Medicines Agency (EMA) has published a detailed review of several studies looking at COVID-19 vaccination during pregnancy. The studies looked at around 65,000 pregnancies at different stages and included pregnant women vaccinated using mRNA vaccines.

The review found no sign of any increased risk of pregnancy complications, miscarriages, preterm births or adverse effects in the unborn babies following mRNA COVID-19 vaccination. Meanwhile, studies continue to show that COVID-19 vaccines are effective in reducing the risk of hospitalisation and death in pregnant women.

Vaccination during pregnancy is common for some diseases. For example, flu vaccine and pertussis are recommended during pregnancy. However, ‘live’ vaccines are not advised during pregnancy.

How long will immunity last?

This is not yet clear: nobody has had COVID-19 – nor the COVID-19 vaccine – for much longer than two years. Over time, it will become clear whether annual booster vaccines would be necessary to maintain protection.