Five years after the pandemic: Researchers are surprised by the coronavirus' development
Many once predicted that the virus would fade into a harmless seasonal cold – but that has not happened. Covid-19 continues to spread all year round.
"The vaccines we have now are crucial for protecting against severe illness, but for a long time they’ve had little impact on whether someone gets infected. The fact that fewer people are getting vaccinated doesn’t really change how much the virus circulates," says Gunnveig Grødeland.(Photo: Lars Ankervold / University of Oslo)
"This is actually very interesting," says Gunnveig Grødeland.
She is a professor of immunology at the University of Oslo and head of the Centre for Pandemics and One-Health Research (P1H).
"We thought SARS-CoV-2 would follow the same pattern as influenza, with a clear winter peak. But the virus has been present more or less all year round," she says.
According to the Norwegian Institute of Public Health (NIPH), test results show an increase in Covid-19 cases in Norway after the summer holidays.
That the virus still circulates year-round is surprising to researchers.
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Not because it mutates faster
For a virus to keep spreading year-round, it needs to find people still vulnerable to infection – those who haven’t developed neutralising antibodies.
A possible explanation could have been that the coronavirus mutates faster than other viruses.
But that's not the case, according to Grødeland.
"In fact, influenza, which has a strong seasonal pattern, changes far more rapidly than SARS-CoV-2," she says.
Expect more predictability
Researchers at NIPH are also monitoring the situation closely.
SARS-CoV-2 still circulates in waves, causing small outbreaks, but without as predictable a pattern as, for example, influenza, explains Trine Hessevik Paulsen, senior physician at NIPH.
Only those who become seriously ill from Covid-19 are currently tested. Therefore, there may be unreported cases with regard to how much of the virus is circulating, believes Trine Hesselvik Paulsen.(Photo: Norwegian Institute of Public Health)
"Many viruses spread throughout the whole year, but most have clear seasonal peaks. Rhinoviruses, which cause the common cold, are a good example. They circulate all year but have two clear peaks – one in autumn and one in spring. We've still not achieved that kind of predictability for SARS-CoV-2," she says.
Paulsen adds that they still expect the virus to eventually settle into a more stable pattern.
There may be unreported cases
Those who don't become seriously ill are rarely tested in primary healthcare.
"Every test comes with a cost, both practical and financial, and there are no longer national recommendations for testing. In hospitals, it's still relevant because test results can affect treatment and infection control, like isolation," says Paulsen.
At the end of the pandemic, NIPH monitored coronavirus in wastewater. This project has now ended.
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"That means there will always be unreported cases with regard to how much Covid-19 is circulating in society, as with all other respiratory infections," she says.
Not due to low vaccination rates
In an article in The Guardian, British researchers write that fewer people getting vaccinated may contribute to the coronavirus still spreading as much as it does.
Grødeland rejects this:
"The vaccines we have now are crucial for protecting against severe illness, but for a long time they’ve had little impact on whether someone gets infected. The fact that fewer people are getting vaccinated doesn’t really change how much the virus circulates," she believes.
For most people today, the coronavirus no longer poses a major threat of severe illness. The exception is older adults. Those over 75 should still get vaccinated, says Gunnveig Grødeland.(Photo: Shutterstock / NTB)
"We're now in the middle of the autumn peak for rhinoviruses, and we saw that Covid-19 infections went down a bit last week. Could it be that rhinovirus suppresses the spread of SARS-CoV-2? We don't know, but the timing of peaks in different respiratory viruses seems to influence one another. Still, this is an area with little solid knowledge," she says.
Mild symptoms for most
The coronavirus will continue to be with us year-round.
"For most people, the risk of serious illness is now low. But older adults remain vulnerable and can still become seriously ill," says Grødeland.
"Among the oldest, it causes as many, if not more, hospitalisations as influenza. That's why following NIPH's vaccine recommendations is a good idea," she says.
The same advice applies to those with underlying cardiovascular diseases, serious chronic lung conditions, and those awaiting organ transplants.
A more conservative approach
Grødeland does not believe vaccine scepticism has increased among those who are advised to get the vaccine.
"I am, however, a bit surprised that more healthy adults think they should take it now. No one has recommended that in recent years," she says.
She believes Norway has a more conservative approach to vaccine recommendations than many other countries.
"In the UK, for example, the flu vaccine is recommended for large parts of the population. In the US there's been an outcry after the secretary of health limited the Covid-19 vaccine recommendations to people over 65 and adults with underlying conditions," she says.
In Norway, the threshold is higher: Vaccines are recommended mainly to prevent serious illness, not to stop people from getting mild infections and missing work, Grødeland explains.
"I think that approach helps maintain trust in vaccines in Norway," she says.
