Winning an Olympic Gold medal requires an athlete to be at the top of their game – but when a competitor has Covid-19, they are unlikely to perform at their best.
Noah Lyles, who won Gold in the men’s 100m event at the Paris Olympics on Sunday, knows this only too well after missing out on victory in Thursday’s 200m final.
After claiming bronze, the 27-year-old American track star revealed that he had, earlier in the week, tested positive for coronavirus, something that may have affected his performance.
Lyles’ diagnosis, and that of dozens of other Olympic competitors, highlights a summer rise in cases that has affected much of the world, including the United States and many countries in Europe.
It follows reports from the World Health Organisation (WHO), which said coronavirus case numbers are increasing in more than 80 nations.
What is happening with infection numbers?
In a press conference in Geneva this week, Dr Maria Van Kerkhove, an epidemiologist with the WHO, indicated that multiple positive cases among athletes were to be expected given the virus' overall prevalence.
"It’s not surprising to see athletes being infected because … the virus is circulating quite rampantly in other countries,” she said.
There have been forecasts that this year could mean the largest summer surge of Covid-19 cases in the US so far, with analysis of wastewater reportedly indicating much higher levels of the coronavirus than in 2023.
Numerous European countries have also been reporting large numbers to the WHO, as have Malaysia and New Zealand, although with testing rates much lower, such reported case numbers may be a less reliable guide to how much SARS-CoV-2, the virus that causes Covid-19, is in circulation in a particular nation.
Prof Eskild Petersen, of Aarhus University Hospital in Denmark and chairman of the emerging diseases task force of the European Society of Clinical Microbiology and Infectious Diseases, told The National that his home country had seen a summer surge, although "it’s fading now”.
As with the US, he said it was wastewater analysis that indicated that case numbers were rising.
The Johns Hopkins Bloomberg School of Public Health said that since the coronavirus has become endemic, it continues to have "dual seasonality”, with two peaks – one in autumn and winter and the other in summer.
One factor behind the summer peak could be that when the weather is very hot, people spend more time indoors with the windows closed and air conditioning on, making the spread of the virus easier.
The background number of cases in the summer of influenza is likely to be lower, so there is less opportunity for flu cases to multiply.
Experts think it is too early to say whether the Covid-19 summer peaks will continue to occur or if the disease will, like influenza, end up with a single annual peak in winter.
Is the number of deaths rising?
What distinguishes the current surge in cases from some of those earlier in the pandemic, Prof Petersen said, is that the rise has not resulted in a large increase in the number of people falling seriously ill. "There’s not been any surge in mortality or hospital admissions that we can measure,” said Prof Petersen, who is a former editor-in-chief of the International Journal of Infectious Diseases.
Immunity generated by having had Covid-19 previously and from vaccination is helping to protect most people from severe effects, Prof Petersen said.
This immunity can be either from antibodies, which tends not to be long-lasting, or it can be cell-based immunity, which typically is longer lasting but which does not prevent infection.
When speaking to journalists in Geneva, Dr Van Kerkhove said that, as well as protection from past infection and vaccination, better treatments and testing, too, were preventing serious illness.
Prof Petersen said that even in parts of the world where vaccination roll-outs had not been comprehensive, levels of immunity were still likely to be high as a result of repeated previous infections.
He said that in parts of tropical Africa, for example, vaccination rates may be low, but many people will have had previous infections.
Also, he said that the fact that a smaller proportion of the population is elderly is another factor that reduces the impact, given that older people are more vulnerable if infected.
"In places like Africa, with a young population, it’s an even less serious problem,” he said.
Should people still be concerned about Covid-19?
Dr Bharat Pankhania, a senior clinical lecturer at the University of Exeter Medical School in the UK, said that while vaccination in particular was offering protection, "repeated infections with this virus are not good for your health”.
He advised people to follow advice that Japan has made for several years of avoiding the three Cs, which are closed spaces, crowded places and close contact with others.
"You will be improving your health and well-being,” he said. "When you’re invited [to have a vaccine] make sure you take it, especially if you’re in a vulnerable group.”
Despite hospital cases not having surged significantly this summer, elderly people and individuals with disabilities remain at increased risk of serious illness and death from Covid-19 when compared to the general population.
Updated vaccines that are more tailored to the main variants circulating are continuing to become available.
A group of variants known as FLiRT, which have separately accumulated the same mutations in the spike protein of the virus, have become common in recent months.
While some Olympic athletes have been competing even while infected, Dr Pankhania said that a more cautious approach was advisable.
"I think you have a duty of care not to infect your fellow athletes,” he said.
