Will vaccines stop the spread or is natural immunity as good as a jab?
Q
How much less likely are you to spread Covid if you have been fully vaccinated?
A
People who are double jabbed are far less likely to catch Covid and then go on to infect others. This has been proven in several studies.
Microbiologist Christopher Byron Brooke at the University of Illinois said last week: ‘[Vaccines] absolutely do reduce transmission. Vaccinated people do transmit the virus in some cases, but the data are super crystal-clear that the risk of transmission for a vaccinated individual is much, much lower.’
A Dutch study found that vaccinated people infected with the Delta variant of Covid are 63 per cent less likely to infect members of the same household who were unvaccinated. Given this, researchers suggested the vaccine could reduce transmission by more than 80 per cent overall.
A team at Yale University looked at data from Israel and came to a similar conclusion: the overall vaccine effectiveness against transmission was 89 per cent.
Earlier studies suggested that vaccinated people might carry ‘as much virus’ as people who are unvaccinated, but the methods used in this research have since been called into question.
Q
How about natural immunity – isn’t that just as good as a jab?
A
All immunity is ‘natural’, whether it comes from catching Covid or being vaccinated against it.
Both events trigger the body’s immune system to react and create cells that are able to recognise and fight off the virus, should it come into contact with it again. However, evidence shows that fewer people will be protected by immunity derived from an infection than with vaccination.
A Danish study suggested that, six months after catching Covid, over-65s had only 47 per cent protection. However, this is older data and reinfection is expected to be more likely with the Delta variant.
New data suggests unvaccinated individuals should expect, on average, to be reinfected with Covid-19 every 16 months, although for those who are older this could be far more frequent, with some scientists suggesting that reinfection in those without vaccination could occur after just three months.