RIVMNational Institute for Public Health and the Environment is carrying out research among families in the Netherlands where someone has contracted the coronavirus SARS-CoV-2. Through our ‘First Few Hundred’ study we want to find out more about the course of the disease. We are gathering more information about how long symptoms last in children and young people, how long it takes to recover, and how they build up immunity to the virus. In addition, we want to know how the virus spreads within a family and if children also pass the virus on to others.

The coronavirus SARS-CoV-2 is primarily spread amongst adults who are about the same age. Within families, the virus is mainly transmitted from adults to children. Children are sometimes infected with the virus, but less often than adults.

First part of the study: 54 families

One hundred families with COVID-19 patients take part in this study. These families participate in the study in cooperation with GGD Utrecht. For the first part of the study, a total of 54 households took part, involving 239 participants, including 185 family members of an infected patient. In total, the study involved 123 adults and 116 children between the ages of 1 and 16 years old. On 23 March the first family was visited. More families will be participating in the second part of the study. In the week of 25 May, new families were visited. It is not possible to sign up to participate. The new households with confirmed COVID-19 children will be selected in consultation with the Municipal Public Health Service (GGD).

Structure of the study

The study is conducted among a hundred families that include persons with a COVID-19 infection. Once there is confirmation that someone is infected, a nurse visits the family as soon as possible. The nurse then collects nose, throat, saliva and blood samples. A questionnaire is filled in, together with the family. This questionnaire includes questions about symptoms, the type of contact with the person who has a COVID-19 infection, the living situation, and any underlying health conditions. The family then keeps track of their symptoms and collects stool monsters for a month. If a family member becomes ill, we take nose and throat samples again and check if this person also has COVID-19. In any case, we take samples from the whole family two more times: 2-3 weeks and 4-6 weeks after the first home visit.

Processing the results

The research period lasts about 6 weeks for each family. The family members keep track of their symptoms for a month, and we collect samples from them several times. For that reason, the results will be processed six weeks after all the families have had their first home visit.

Initial results

Although the study is still ongoing, preliminary results are already available. The results of the study on COVID-19 in Dutch families confirm the impression that children do not play a significant role in the transmission of the virus. They may become ill, but their symptoms are often very mild. This is a marked difference from the seasonal flu (influenza), where we often see children passing the virus to each other or to adults. This appears to occur far less frequently for the novel coronavirus. The findings from the study are in line with the results of research being done in other countries, including studies in China and South Korea. Following peer review, RIVMNational Institute for Public Health and the Environment published the results in the Nederlands Tijdschrift voor Geneeskunde (NTVG), the leading medical journal in the Netherlands. Read the article in NTVG: 'De rol van kinderen in de transmissie van SARS-CoV-2' (in Dutch).