Tom Britton: We do not reach herd immunity during the winter

In the spring of 2020, Tom Britton predicted that the Stockholm region could reach herd immunity as early as the end of May.

But that did not happen.

He states two reasons why the calculations did not work out that time.

On the one hand, the number of unreported cases was not as large as he had expected, and on the other hand, society changed with restrictions faster than calculated, which slowed down the spread of infection.

- I thought that significantly more people would have been infected.

66 percent immune

Herd immunity is also related to which virus is in circulation and how contagious it is.

In the spring of 2020, Tom Britton estimated that 60 percent of the population would have needed to achieve immunity for society as a whole to achieve herd immunity.

With the more contagious delta variant now dominating, an immunity level of around 80 percent is required, according to Britton.

If the omnikron variant proves to be even more contagious, the figure may need to be adjusted upwards even more.

According to a new calculation from Tom Britton, 66 percent of the population in Sweden currently has an immunity to the virus.

But the estimate is relatively rough and there is a lot of uncertainty in the model, he explains.

- Between 60 and 70 percent is more reasonable to say.

Restrictions for the summer

How long can they then take to achieve herd immunity?

At least it will not happen during the winter, according to Tom Britton.

And we may never reach all the way.

But if the proportion of fully vaccinated rises to around 80 percent, we may be able to reach a situation where we no longer need severe restrictions, he says.

- Then maybe it would be enough with these basic things like staying home when we have symptoms and washing our hands, and it's not the whole world, he says.

He emphasizes that herd immunity does not occur at a sharp border but should rather be considered as a sliding scale.

- We are a bit away at the moment and hopefully we can get a little closer.

By the summer, I do not think we will need any restrictions.