Will COVID-19 vaccines need to be redesigned later this year? As evidence emerges suggesting some new variants of the SARS-CoV-2 may partly evade current COVID-19 vaccines, experts are exploring how rapidly vaccines could be tweaked to cope with changes.
It should be said that it remains unclear just how effective vaccines developed last year will be. They may be highly effective; they may prevent hospitalisation and death; they may have limited efficacy – we simply cannot say for certain at this point.
Nevertheless, industry scientists have indicated that they could rework existing vaccines within weeks. As they are not starting from scratch, researchers expect to move quickly if needed.
Large clinical trials accounted for most of the time spent developing the first round of vaccines. But politicians and regulators have said smaller, shorter trials will suffice this time, as long as developers are tweaking one of the existing approved vaccines.
COVAX, the global programme to bring COVID-19 vaccines to high-risk populations in lower-income countries, is also looking closely at how its plans would be affected if rich countries began vaccinating some of their highest risk citizens with a second generation jab.
Dr Soumya Swaminathan, Chief Scientist at the WHO, says existing vaccines are likely to offer some protection against all variants of SARS-CoV-2. Even if boosters are needed at some stage, with so many people awaiting their first dose, it may be too soon to consider offering a second or third dose to people in rich countries.
‘The good thing about all the vaccines that have been approved is that they offer a lot of protection against severe disease, hospitalisation and deaths,’ Dr Swaminathan said. ‘And that’s what we want: we want to reduce deaths, we want to prevent people from getting sick and going to hospital.’
Referring to concerns about vaccine efficacy against some of the new SARS-CoV-2 variants, she struck an optimistic tone: ‘All of the vaccines that are approved are very likely to still protect against hospitalisation and death.’
Dr Swaminathan said that people in countries with access to vaccination should have their vaccines, adding that the WHO is working with regulators to determine when a vaccine change might be appropriate and what clinical and immunological data might be needed.
The European Medicines Agency (EMA) has issued guidance on adapting approved vaccines, prompting a quicker process than the rigorous scrutiny applied to first-time applications.
Smaller trials would be accepted in cases where a variant-proof vaccine is only a minor update on existing approved vaccines, it said, making the approach similar to that taken in approving flu vaccines every year.
The European Commission’s HERA Incubator, a biodefence initiative, will have a leading role in ensuring fast-track approval of updated vaccines.
‘The assumption is that a new variant vaccine would largely rely on the same technology and platform as the ‘parent’ vaccine – a vaccine already approved in the EU for the prevention of COVID-19,’ the European Medicines Agency says. ‘The difference would be in the specific structure (antigen) selected to trigger the immune response in the body.’
The effectiveness of a single dose, as a booster shot, in previously vaccinated individuals should also be studied, the regulatory adds. From the perspective of individuals having a booster vaccine, the question will arise as to whether a second or third dose of a COVID-19 vaccine would need to be of the same kind as their previous dose(s).
There are already some studies taking place looking at having two doses of different vaccines. In theory, this approach may prove to be even more efficacious than having two doses of the same vaccine, particularly when it comes to viral vector jabs (click below for explanation).
As usual, post-authorisation studies would continue to monitor long-term safety and effectiveness of variant COVID-19 vaccines.
‘The variant vaccine is expected to be produced by the same manufacturer, and in line with processes and controls used for the parent vaccine,’ according to the new EMA guidance. ‘The manufacturer will need to generate data that show that the quality of the variant vaccine complies with the standards set for the parent vaccine.’