With all the questions in the news we asked experts Matt Keeling and Sam Moore, epidemiological modellers at Warwick University and members of the JUNIPER modelling consortium, if and when the vaccine will stop the pandemic. Here is what we learned.

At the moment nobody knows. Keeling and Moore are currently doing some modelling to get answers to the question, but this is still work in progress. The question involves multiple uncertainties: how does the vaccine act; how many people will get vaccinated and when; what controls will be in place until vaccination is complete?

What is certain, and what keeps people like Keeling and Moore awake at night, is that uptake is crucial. If not enough people get themselves vaccinated then the epidemic won't be stopped. This is particularly true because, as we saw here, we don't yet know whether the vaccines actually stops transmission of the virus, which means that we can't rely on herd immunity to kill the epidemic. Ideally every single person in the country who can get the jab should get the jab, Keeling and Moore say.

What is also certain is that much depends on the social distancing measures remaining in place as the vaccinations are happening. If there isn't enough social distancing, then the R number will be sufficiently large for the exponential growth of the epidemic to outrun the vaccination effort.

A lot here depends not just on government guidelines, but also on our personal decisions. We have probably all dreamed of instant post-vaccination hugging and kissing, but there's a real danger in letting our guard down too soon. We will all require two jabs and therefore it will take a good month or so until the vaccine becomes effective. Even then, if the vaccine doesn't stop transmission but only symptoms, we could still pass the virus on. So as painful as it may be, Keeling and Moore say, we need to keep sticking to the rules for a while longer.

Another thing we don't yet know about the vaccine is how long it will protect us for. If protection wanes when the virus is still making its rounds then future outbreaks are possible and will need to be countered with a new vaccination campaign. There is also of course the question of how any new variants of the virus affects vaccination. Luckily all available evidence indicates that the existing vaccines will still be effective against the new variant that arose in the UK in September 2020. More generally it's worth bearing in mind that influenza mutates every year but scientists now have a good "vaccine toolbox" to use to keep it at bay. The knowledge gained from this practice will be beneficial in responding to any COVID-19 mutations as well.

As Keeling and Moore can't stress enough, we are in an unprecedented situation dealing with a rampant, deadly live pandemic. Vaccination is our only hope and it's safe for the general public. If you can get the jab, then please do so. It's the only way to protect yourself, to protect those more vulnerable than you, and to help the world get back to normal.

Return to our COVID-19 vaccines FAQ

About this article

Matt Keeling

Matt Keeling is a professor at the University of Warwick, and holds a joint position in Mathematics and Life Sciences. He is the current director of the Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER). He has been part of the SPI-M modelling group since 2009.

Sam Moore is a postdoctoral research associate who has been working on vaccination modelling for Covid-19 after joining SBIDER within the University of Warwick at the start of the pandemic earlier this year.

Sam Moore

Both are members of JUNIPER, the Joint UNIversity Pandemic and Epidemic Response modelling consortium. It comprises academics from seven UK universities who are using a range of mathematical and statistical techniques to address pressing question about the control of COVID. The universities are Cambridge, Warwick, Bristol, Exeter, Oxford, Manchester, and Lancaster. You can see more content produced with JUNIPER here.

Marianne Freiberger and Rachel Thomas are Editors of Plus.