Group of infected people with few complaints probably larger than expected

Even before the carnival weekend, some of the employees of two Brabant hospitals infected with the coronavirus started having cold complaints – and thus before the first patient with Covid-19 was discovered in the Netherlands. That appears from the preliminary report of a study of 86 health care workers who had been diagnosed with the virus in the first weeks of the outbreak. Most had remarkably mild symptoms, and almost half had no fever. More than half of these hospital workers continued to work during the first few weeks, when the criteria for suspecting Covid-19 were even stricter. On the basis of these results, the Dutch researchers recommend that health care workers with colds should also stay at home without a fever.

“The study confirms our suspicion that the coronavirus was already circulating in the Netherlands for the first Covid-19 patient in the Netherlands was reported on February 27 in Tilburg,” said Jan Kluytmans, MD, microbiologist at Amphia hospital and leader of the study. “This fits in with the fact that the infection rate in Brabant was increasing so quickly. It also indicates that the group of infected people with unnoticed symptoms may be larger than we think. ”

64 percent mention stabbing muscle pain

As the pandemic progresses, it turns out that the coronavirus has treacherous faces, with a range of mild complaints, especially among younger people, and a very serious course for the elderly and people with chronic diseases.

The complaints of the Brabant care workers in this study also vary. Coughing occurred in three quarters of the people, as did an overall feeling of malaise, but also severe, stabbing muscle pain was mentioned by 64 percent. In addition, a fever, headache or runny nose occurred in over half, and a sore throat and tightness in nearly 40 percent.

Between 7 and 12 March, more than 1,300 employees of the Amphia Hospital in Breda and the Elisabeth Two-City Hospital in Tilburg were tested for the study, who had had fever or mild respiratory complaints in the ten days before. That was regardless of whether they had been in the outbreaks of northern Italy or China – one of the criteria for a suspected corona infection at the time. Of them, 86 people were found to be infected with the coronavirus, and almost no one was linked to those risk areas.

Seven hospital employees already had complaints before the first corona patient was discovered, two of them even on February 19 and 21, before the carnival started on the 23rd. “The symptoms start between 3 to 12 days after you have been infected, so the infection may have been calculated in early February,” says Kluytmans.

Unobserved cases

It is not known where those people contracted the coronavirus. “They have no connection with infected patients we know. They are likely to be infected by other undetected cases that have been linked abroad, ”said Kluytmans. It could also be that someone already had another cold virus, and on top of that later got the corona virus, he agrees. “But I think the chance is small.”

In several models and studies, scientists worldwide are trying to estimate the size of that group with mild, unnoticed symptoms. The findings range from ten to fifty percent. In Iceland, where a relatively large proportion of the population is tested, 218 of the 3,787 residents tested were positive. Half of them had no complaints.

“We think there is a large group of people with few complaints, and we now want to map them quickly with blood tests for antibodies. RIVM and Erasmus MC in Rotterdam are now optimizing those tests so that they are reliable enough. ” Kluytmans hopes that many people have already been infected without noticing it. “That herd immunity may turn out to be higher than we thought.”

Also read: Why are men more vulnerable than women? And 37 other questions about the corona virus

Letting go of fever as a criterion to stay at home

Because fever was not a symptom in half of the infected healthcare workers, the researchers recommend that healthcare workers let go of fever as the first condition for staying at home. That says still in the general principles of the RIVM. “The downside is: if you keep all those people at home, you can have capacity problems,” says Kluytmans. “But in Brabant hospitals, employees now also have to stay at home when they cough and feel sick without a fever, and so far we can continue to work well with these wider criteria.”

The more and more criteria are released in the guidelines and principles of the RIVM, as more information becomes available about the coronavirus. These new insights will also be taken into account in the advice of the Outbreak Management Team, RIVM spokesperson Coen Berends says.

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