Omicron Covid vaccine: what you need to know about the new UK booster

The UK has become the first country to approve Moderna’s bivalent Covid-19 vaccine - a groundbreaking new jab which targets both the original strain of the SARS-CoV-2 virus and the newer Omicron variant – with the rollout of doses set to begin within weeks.

Health officials are banking that providing the most vulnerable populations with booster doses of the jab will help prevent hospitalisations from the now dominant BA.5 strain over Covid-19 over the winter months. It is hoped that this will minimise pressure on the NHS, currently creaking under the combined toll of providing routine care and dealing with the post-pandemic backlog.

“In line with previous years, we expect to see levels of circulating SARS-CoV-2 increase during the winter months,” says Deborah Dunn-Walters, Professor of Immunology at the University of Surrey. “Vaccination is still the safest and most effective way to protect yourself from becoming very ill with Covid-19. It is important to take up the offer of a booster vaccine if you are offered it.”

Below is our guide to everything you need to know about the new vaccine:

What exactly is it?

Known as Spikevax or mRNA-1273.214, the vaccine is an updated version of the original Moderna jab which was made available in the UK from the end of 2020.

It works by using messenger RNA (mRNA) to generate an immune response against both the spike protein from the original Wuhan strain of Covid-19, and the spike protein associated with the BA.1 subvariant of Omicron.

Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene and Tropical Medicine (LSHTM), explains that the similarities between the bivalent vaccine and the Moderna vaccine already in use have allowed the Medicines and Healthcare Products Regulatory Agency (MHRA) to fast-track it.

The MHRA approval is based on neutralising antibody responses to different variants of Covid-19 observed in the blood of people who received the vaccine as part of a trial, rather than long-term data looking at whether it reduces risk of hospitalisation or death.

“We now know from many studies that this antibody response is, to a degree, predictive of the clinical effect in prevention of infection, and hence admission to hospital or death,” says Evans. “It would take very much larger trials to show such effects conclusively, but we can be confident it is likely to show better clinical efficacy against the Omicron variants than the original vaccine alone.”

Will it work better than the options we already have?

Trials conducted on 437 people showed that the new vaccine yielded a markedly stronger immune response compared to the existing Covid-19 jabs in use, with participants producing 70% more antibodies.

Crucially, Moderna claim that the vaccine also displayed potent responses against the newer BA.4 and BA.5 forms of Covid-19, which are currently the dominant strains in the UK. The company’s chief medical officer Dr Paul Burton has previously suggested that the new jab can boost a person’s antibodies to such high levels that it may only be needed annually.

However, scientists point out that it is still hard to predict how antibody responses will actually translate into protection against infection and hospitalisation, especially given that the Moderna trial only consisted of a few hundred people.

“Availability of a bivalent vaccine is good news, but how much of a difference it would actually make remains to be seen,” says Professor Beate Kampmann, Director of the Vaccine Centre at LSHTM. “It has not yet been widely tested in large heterogeneous population groups.”

Who’s going to get it?

Within hours of the MHRA’s approval announcement, the Joint Committee on Vaccination and Immunisation (JCVI) recommended the use of the new vaccine in a booster campaign beginning next month.

Approximately 29 million people in the UK will be eligible for the new jab, including all over-50s, frontline health and care workers, younger people with chronic conditions, pregnant women, and anyone over 5 who shares a house with somebody with a compromised immune system.

The vaccine will be made available through GP surgeries and pharmacies, with the oldest and most vulnerable invited first, as in earlier phases of the vaccination program.

There is currently no indication of whether the vaccine will be made available to the rest of the population at a later date, with the focus being on preventing those most at-risk from becoming seriously ill, rather than stopping the young transmitting it to older relatives.

Will it have more or fewer side effects than current jabs?

It is thought that the side effect profile will be unchanged to the original Moderna jab: a sore arm for a day or two, and mild fever for some.

Will there be any further bivalent vaccines in the pipeline?

An updated Pfizer vaccine that works in a similar way is also expected to be approved in the next few weeks. However, it has been announced that the Oxford-AstraZeneca vaccine will not be updated.

Will we have a choice or will we get what we’re given at the clinic?

The UK Vaccine Taskforce is believed to have already contacted Moderna to request that all future vaccine shipments are of the new jab. However the company has said that only 13 million doses of the new vaccine are currently available, raising question marks over whether everyone eligible will get it.

It is thought that if there are insufficient doses of the new vaccine, then vaccine centres will offer a booster dose of the original Moderna or Pfizer vaccine. Those who are unable to receive a mRNA vaccine because they have a severe allergy to one of the vaccine ingredients, will receive a Novavax vaccine. The AstraZeneca jab is no longer being used, as the company is now concentrating on antivirals.

Scientists said that the exact protocol still needs to be laid out by the JCVI.

“We need to await the JCVI’s view on whether the bivalent vaccine should be used for all those for whom the autumn booster has been recommended, or if supply constraints will result in targeting this vaccine form to a subset of that population,” says Penny Ward, visiting professor in pharmaceutical medicine at King’s College London.

What if you’ve already had Covid this summer – do you still need it?

Scientists recommend vaccination to anyone classified as being in the vulnerable categories who has not received a booster within the last three months, regardless of whether they have recently had a bout of Covid-19.

It is thought that the combination of natural infection and vaccination can elicit an even more powerful antibody response, known as hybrid immunity.

“Boosters are an important intervention for the winter period and should be taken up across age groups, as recommended, with the most vulnerable to be first in line,” says Kampmann.

What happens if a new variant comes along?

While it is hoped that the new vaccine will offer at least some protection against any future sub-variants of Omicron, it is less clear how protective it might be against another emerging strain which contains different mutations.

Scientists caution that there is a possibility that Omicron-targeted immunity may push the virus down other evolutionary paths, which may force vaccine developers to release further updated versions. However it is hard to predict when or how quickly that may occur.

Jonathan Ball, Professor of Molecular Virology at the University of Nottingham says that overall, the development of a new vaccine is positive news for protecting the vulnerable against newer variants of the virus.

“Targeting two different flavours of the coronavirus spike protein means that the new vaccine should provide people with better protection against the Omicron variants,” says Ball. “The virus is unlikely to stand still, but that said, unless there is a major shift in the virus, immunity will continue to protect the vast majority from serious disease caused by emerging variants.”