After nearly nine months of coronavirus restrictions, there may be a light at the end of the tunnel.
The UK is the first country in the world to approve Pfizer’s jab for widespread use, with the NHS standing ready to begin immunising care home residents and staff next week.
With an effective vaccine long been hailed a route back to life as we knew it, many are undoubtedly wondering how many people have to receive the jab to achieve herd immunity, freeing us of future lockdowns.
Herd immunity occurs when an infection cannot take hold in a community. It can come about in two ways if a sufficient number of people have overcome a virus and are now immune, or via vaccination.
In March, the UK’s chief scientific adviser Sir Patrick Vallance told ITV News: When you look at infections across whole communities, when you get up to about 60% who’ve had it, you get something like herd immunity, which means we’re then all a bit protected from it.
So if it does get to that level, that provides quite a lot of protection going forward. This was before officials rethought their strategy to just suppress the outbreak to create herd immunity, with a nationwide lockdown being introduced 10 days later.
Also speaking in March, Professor Martin Hibberd, from the London School of Hygiene & Tropical Medicine, said: When about 70% of the population have been infected and recovered, the chances of outbreaks of the disease become much less.
In a good scenario, the 70% infected, recovered and immune would be people who were expected to have mild disease and the 30% who were vulnerable to severe disease would be protected by this herd immunity. Eight months later, the bar for herd immunity was thought to be higher.
In November, Professor Julian Savulescu, from the University of Oxford, said: The exact percentage of the population that would need to be immune for herd immunity to be reached depends on various factors, but current estimates range up to 82%.
The rate of immunisation required to achieve herd immunity varies between viruses, depending on how infectious they are and how effective a vaccine is.
With measles for example, 95% of people need to be immunised for everyone to be protected.
When asked about the number of Pfizer vaccines needed to achieve herd immunity, the firm’s UK country manager Ben Osborn said: It’s not for Pfizer to say how many should be vaccinated.
That’s why we have the independent group JCVI [joint committee on vaccination and immunisation].
Professor Ralf Rene Reinert– vice president of Pfizer Vaccines agreed, adding herd immunity cannot be speculated at this stage, but could be gauged by looking at the rate of protection in cities that have endured large outbreaks, like those in northern Italy. Hopefully I can answer this question at the end of next year, he added.