Man houdt tablet vast met vragenlijst over Long COVID

Three months after infection with the coronavirus SARS-CoV-2, almost half of people still report one or more long-term symptoms, such as fatigue, difficulty concentrating and loss of smell. This is almost twice as often as people who did not have COVID-19, and more than 1.5 times as often as people who had other respiratory infections. This is evident from the interim results of the RIVM Long COVID study. Fully vaccinated participants under 65 years old were less likely to report symptoms involving smell and taste after three months, but the other long-term symptoms did not show any difference between people who were not vaccinated, partly vaccinated or fully vaccinated at the time of infection.

These findings come from surveys conducted between May and December 2021 among a total of 14,572 participants. These included 9,166 people who signed up for the study shortly after testing positive for COVID-19. The control group consisted of 5,406 people who did not have COVID-19. They either signed up on their own initiative after testing negative or were invited in a letter sent to the general population.

After three months, symptoms such as tiredness (31%),shortness of breath (16%), loss of smell (12%), concentration problems (15%) and difficulty handling busy surroundings (13%) were reported significantly more often among people who had had COVID-19 compared to people who had not. In many cases, tiredness (28%) and/or cognitive problems (15%) and shortness of breath (13%) are so severe that normal daily activities are severely disrupted.

Effect of vaccination

The effectiveness of the various COVID-19 vaccines in preventing hospital and ICU admission has been demonstrated worldwide. It is less clear whether vaccination also offers protection against long-term symptoms if someone has a SARS-CoV-2 infection after vaccination, and to what extent. In this study, it was also possible to investigate whether participants under 65 years had experienced protection from vaccination prior to SARS-CoV-2 infection. Participants under 65 years of age who had been fully vaccinated were less likely to report problems with smell and taste after 3 months than participants who had not been vaccinated. The study did not find any difference in how often the other long-term symptoms occurred in people who were not vaccinated, partly vaccinated or fully vaccinated at the time of infection. International studies on vaccine effectiveness in preventing long-term symptoms show mixed results. Further assessment is therefore needed to make informed statements on this topic.

This study not only shows that a large percentage of COVID-19 patients continue to have symptoms after recovery from the acute illness, but also indicates that these symptoms are much more common in these patients than in people with other respiratory infections and in the general population. The fact that the symptoms also frequently occur in people who have not had COVID-19 illustrates the challenge for healthcare professionals in clinical practice to determine whether a patient’s symptom is caused by Long COVID (also known as post-COVID), or by some other factor.

During this round of the study, SARS-CoV-2 infections primarily involved the Alpha and Delta variants of the coronavirus. Whether these results continue to hold true after infection with the Omicron variant will become clear from the next interim results in the Long COVID study.