First there was Alpha, then there were Alpha, then there were Alpha, then there were Delta. The world is getting to grips with the Omicron variant thanks to the efforts of scientists in Africa. Scientists are concerned that the vaccines we are currently using may not be as effective against Covid-19 because it has a number of different mutations. The UK's Joint Committee on Vaccination and Immunisation (JCVI) has recommended that all over-18s in Britain should be able to get a Covid booster shot if they haven't had it in three months.
Boosters are designed to make sure that the UK population has a high level of immunity, so that the spread of Omicron won't cause a lot of deaths. It is too early to say if the vaccines we are currently using will be effective against the new variant.
How do boosters work? Data from observational studies show that the immunity built up by exposure to both vaccines and the virus reduces over time. When someone comes into contact with the sars-coV-2 virus, they can reduce the severity of their illness and the chances of them spreading it by being exposed to viral proteins contained within the vaccine.
A recent UK clinical trial investigated whether the same vaccine for the first two jabs and the booster improved the immune responses of people who had a different vaccine for their booster. Some people who had received two doses of either Pfizer or AstraZeneca vaccines were given a third dose of one of the Covid vaccines as their boosters in a trial. Six out of seven of the vaccines increased the amount of antibody in the body after they were given.
Predicting the long-term protection provided by a vaccine is not easy. We often measure the level of antibodies in the blood as a marker of immunity, but we don't know much about the immune cells that are important in fighting infections such as sars-coV-2
Knowing the level of antibodies doesn't give us any information about the effectiveness of a vaccine at preventing severe disease that results in hospitalisation or death. The most important question for most people is whether they will die or get sick from Covid-19. The CoV-Boost trial collected further data over the course of a year to answer questions in the future.
We don't know if the Omicron variant will result in us needing to get more boosters. It is possible for several reasons. It is possible that our immune systems need to be exposed to a certain type of viral proteins in order to generate an effective immune response. Over time, this will become clear. There is a risk that the current vaccines will be different to the ones that will be needed in the future. The first generation of vaccines took more than a decade to be produced.
The Coalition for Epidemic Preparedness Innovations launched a funding call to encourage the development of Covid-19 vaccines that provide protection against multiple types of coronaviruses, avoiding the need for a new vaccine for every new variant that emerges.
It is impossible to talk about Covid booster vaccinations without mentioning the importance of vaccine equity. Many people, including healthcare workers and people at risk of severe disease, have yet to receive a booster dose of the Covid vaccine. We need to drive down viral transmission to prevent the emergence of Omicron. We will eventually be dealing with the emergence of variant that are not substantially affected by the vaccines we have available, and the ground we have gained over the past year will be lost, along with many lives and the wellbeing of thousands upon thousands of people.
You can think of a house fire. There are high levels of sarco-coV infections in multiple territories. The UK is one of many high-income countries trying to tackle the fire by making sure there is enough water available. The fire will always be there if infections are allowed to rage elsewhere because of a lack of global vaccines. If you roll out boosters in one country, without delivering vaccines in low- and middle-income countries, you won't prevent the house from burning down or keep us safe.
The University of Cambridge has a lecturer in intensive care medicine.
