Over 80 percent of the adult Swedish population has received a vaccine dose against covid-19.

In addition, almost 60 percent have received a second dose and are thus considered to have good protection against serious illness.

With the knowledge about pandemics that existed before the new coronavirus hit the world, it had meant that flock immunity was waiting around the corner.

Then came the mutated variants and put all the calculations to an end.

Risk of new wave

Now that the spread of infection is on the rise again, there is therefore a risk of a new wave.

Tove Fall, professor of molecular epidemiology at Uppsala University, makes that assessment.

- In many countries where vaccination has gone even further than Sweden, there has still been a sharp increase in infection in recent times.

Among other things, I think of Israel, Great Britain and the United States, she tells SVT News.

The assessment of what can be considered an "acceptable" level of spread of infection can be made based on several factors, says Fall.

In addition to the burden on healthcare, the risk of long-term problems after illness also plays a role.

However, the fact that the vaccine does not provide 100% protection and that some people cannot be vaccinated for medical reasons gives reason to keep the infection in check.

- We must at least avoid the huge waves of infection that this group can not protect themselves against.

"We are still learning"

Ali Mirazimi, professor of clinical virology at Karolinska Institutet, also thinks that there is reason to be cautious.

There are no predetermined values ​​for which level of spread of infection minimizes risks.

Especially not in the situation we are in now.

- We are still learning.

But eventually, when we know how well the vaccine protects, we can not just look at the spread of society.

This virus has come to a halt.

And it is precisely the knowledge of how long the vaccine protects against disease that he sees as crucial for the continued pandemic fight.

- Today we also lack good drugs against covid-19.

If we had, we could really take care of those who come to intensive care and save lives.