People who have been fully vaccinated could need COVID-19 booster shots within a year to 18 months. The research is ongoing, however, it's important that we know what to expect. Why are both the second dose of a two-dose vaccine and future vaccine doses called "booster shots"? And, why are future, repeat vaccinations possibly necessary?
Generally speaking, vaccine booster shots have been a part of our lives for years.
"Immunisation or vaccination is really the most effective preventative measure we have against serious diseases," says Dr Noluthando Nematswerani, Head of the Centre for Clinical Excellence at Discovery Health. "Looking at the range of vaccines that a person receives from birth to adulthood, some vaccines offer lifelong immunity after a single dose. In other cases, booster shots are needed to gain the maximum possible immune response."
"That's because the protection offered by vaccines wears off over time. Polio vaccine booster shots are recommended every 10 years for people who travel to places where polio is common, or those who work with people who have the disease. Children commonly have vaccine booster shots for Hepatitis A and B, measles, mumps and rubella (MMR), and more diseases. Teenagers and adults may need vaccine booster shots for MMR, shingles, pneumonia and more illnesses."
"Another example is in the case of viral illnesses like influenza (the flu), where prevalent flu viruses mutate. This means they change from year to year, making the previous year's vaccine less effective, and requiring an updated flu vaccine every year," explains Dr Nematswerani. "Flu shots are also important for people who are pregnant or who have chronic illnesses that put them at risk of severe illness if they contract the flu virus."
Overall, depending on the type of vaccine you get, you might get a booster shot some weeks, months, or even years after your first vaccine dose.
It is possible to contract a disease after being vaccinated against it? If so, why should we get vaccinated?
"Vaccines train your immune system to fight an infectious disease so it recognises the disease and quickly deals with it, should we become infected with it after being vaccinated," says Dr Nematswerani. "It's important to keep in mind that having any vaccine does not guarantee that you will not become infected with the disease it protects against. What vaccines do is make sure that we are far less likely to experience severe illness, hospitalisation or death from the disease we have been vaccinated against."
- We call COVID-19 infections in people who have been vaccinated against the disease "breakthrough infections". So far, most such cases are asymptomatic (COVID-19 is detected where people test positive during routine testing) or cases of mild illness.
With this in mind, let's explore COVID-19 booster shots
"COVID-19 vaccines are all considered very effective, especially when it comes to preventing hospitalisation and death in people who contract COVID-19," says Dr Nematswerani. "The conversation about vaccine booster shots stems from this fact: it's still unknown how long the available COVID-19 vaccines can protect people against the virus, and when a booster shot is needed to "top up" our immunity against this disease to get our immune response back up to what it was when we were first fully vaccinated."
"As scientists learn more about the virus that causes COVID-19, they'll understand more about how long immunity from the available COVID-19 vaccines will last. Current research shows that vaccine related immunity can last for a minimum period of 6 months and longer. This will continue to be monitored as more people continue to get vaccinated over a longer period of time."
COVID-19 vaccine booster shots might be needed to deal with variants
"Vaccine developers are also developing booster shots to keep up with the emergence of COVID 19 viral variants. So far, studies suggest that the vaccines we have on hand are effective against emerging variants, but they may not provide quite as much protection against the new strains as against the original COVID-19 virus they were designed to protect us against."
- Understand how the COVID-19 virus works - Why do viral variants develop?
- The World Health Organization (WHO) has assigned letters of the Greek alphabet to COVID-19 virus variants currently in circulation around the world to make them easier for us to talk about and understand.
- The Alpha variant was first detected in the United Kingdom (UK) in September 2020. The Beta variant was first detected in South Africa in May 2020. The Gamma variant was first detected in Brazil in November 2020. The Delta variant was first detected in India in October 2020.
Looking at the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccine booster shots in more detail
Some COVID-19 vaccines are given in two doses, like the Pfizer-BioNTech vaccine (which is being rolled out in South Africa) and the Moderna vaccine, which are both based on mRNA technology).
- The first dose initiates an immune response, and the second dose - which is called a "booster shot" and is given after a particular amount of time - strengthens this response.
- You're likely to have mild, flu-like side effects after your second dose.
The manufacturers of the Pfizer-BioNTech and Moderna vaccines have indicated that people who have had both doses of these vaccines probably need a booster shot to keep their immunity up. These are already in development. They have also indicated that we will likely need to get COVID 19 vaccine shots yearly, much like the flu vaccine.
Local studies into the single-dose Johnson & Johnson vaccine indicate that people could need to get a booster shot for this vaccine less than a year after getting vaccinated. This vaccine, which is based on DNA or viral vector technology, has been rolled out in South Africa in Phase 1 of the local vaccine programme and will be rolled out in future.
- Read more on Pfizer-BioNTech COVID-19 overview and safety.
- Read more on Johnson & Johnson's Janssen COVID-19 overview and safety
Have you had your first Pfizer-BioNTech vaccine dose? When will you have your second dose or booster shot?
Read up on the current guidelines for people being vaccinated in South Africa, and a fascinating study emerging from the UK. This study shows that delaying the administration of a second booster vaccine shot can in fact strengthen the immune response significantly.
All medical information found on this website including content, graphics and images, is for education and information objectives only. Discovery publishes content to help to promote a better understand of COVID-19 and COVID-19 vaccinations. The content covered is an overview of key concepts and is not exhaustive in nature. We encourage further reading from other credible sources where necessary.
South African organisations:
- National Department of Health's dedicated COVID-19 portal: https://sacoronavirus.co.za/
- National Institute for Communicable Diseases' (part of the National Health Laboratory Service) dedicated COVID-19 hub
- South African Health Products Regulatory Authority (SAPRHA - part of the National Department of Health).
- South African Medical Research Council (SAMRC)
- South African Medical Journal (SAMJ)