Dutch Research On Long Covid Shows 50% Of Study Participants Have 1 Or More Symptoms 3 Months After Becoming Infected With Coronavirus

The Dutch RIVM (Center for Infectious Disease Control – CDC counterpart in the Netherlands) is conducting a long-term study on long Covid. The agency released interim results on Tuesday, June 21^st, which show that approximately 50% of patients enrolled in a large ongoing study still have one or more symptoms three months after becoming infected with the coronavirus SARS-CoV-2. In addition, among adults under the age of 65, researchers detected no difference between those who are vaccinated and unvaccinated in terms of most long Covid symptoms, except for sense of smell and taste. Vaccinated adults reported less loss of smell and taste than than those who were unvaccinated.

Long Covid is a hotly debated subject. In particular, some experts have worried about lack of clarity around long Covid’s characterization, and causal inferences which aren’t necessarily well established. And so, the key questions become, what exactly are long Covid symptoms, and how likely is it that a coronavirus infection caused them?

There isn’t a firm consensus on long Covid’s precise definition, and causality is still being analyzed by clinical researchers. Yet, since fairly early in the pandemic, a broad set of symptoms we now refer to as long Covid – the literature used to label sufferers as long-haulers – has been very well documented. The Dutch RIVM, in particular, has meticulously collected data on long Covid, both to characterize the syndrome and attempt to figure out what’s causing symptoms.

It’s evident that many people who contract the coronavirus struggle for months with lingering Covid-19 symptoms which can be debilitating. Patients exhibit shortness of breath, extreme fatigue, intermittent fevers, cough, concentration issues, chest pressure, headaches, and heart palpitations, among other symptoms.

There is a very wide range in estimates of long Covid prevalence among those who recover from a symptomatic coronavirus infection. A University of California Davis study found that 10% of Covid-19 patients suffer from long Covid symptoms. In a CDC-sponsored study, it was estimated that around 20% of adults under 65 who recover from Covid-19 experience at least one health condition that could be considered long Covid. Here, CDC researchers identified persistent health problems in different organs of the body, including the heart, lungs, and kidneys. Yet another study suggested that 30% develop at least one long Covid symptom over time.

Fatigue, shortness of breath, brain fog, and loss of smell are particularly common long-term effects of Covid-19. This is apparent from the studies mentioned above, but also the interim results of the RIVM’s study released on June 21^st. For some, symptoms are relatively minor. For others, however, they can be disabling and life-altering.

The preliminary findings from the RIVM investigation refer to data gathered from May to December 2021. As such, they concern people who became infected with the Alpha or Delta variants of the coronavirus.

The results derive from a health survey questionnaire taken by a total of 14,572 participants. 9,166 people took the survey shortly after testing positive for SARS-CoV-2. The control group consisted of 5,406 people who tested negative for the coronavirus and applied to take part in the survey or were invited by letter from the general population. RIVM requested that all survey participants fill out questionnaires about their health at intervals of three months.

Around 33% of study participants who became infected with coronavirus still suffer from fatigue three months later. Persistent shortness of breath occurs in 16% of respondents, 15% have ongoing brain fog, and 12% have chronic loss of their normal sense of smell and taste for at least three months after their initial infection.

What’s striking is that these reported symptoms are 1.5 times more common among Covid-19 patients than among those who have had other (non Covid-19) respiratory infections.

The Dutch research also demonstrates that fully vaccinated people under 65 years of age who contracted coronavirus have fewer problems with smell and taste after three months. For other symptoms, however, no difference was found between vaccinated and unvaccinated people.

The RIVM will continue to follow up with study participants for at least one year. And, the agency will eventually include results from those who became infected with the Omicron variant.

The Dutch investigation not only shows that a large percentage of Covid-19 patients continue to have symptoms after recovery from the acute, initial coronavirus infection, but also suggests that the constellation of long Covid symptoms is much more common in these patients than in people in the general population, and in patients who experienced other (non Covid-19) respiratory infections.

While there continue to challenges regarding how to precisely define long Covid and how to determine cause and effect, ignoring or downplaying the long Covid syndrome isn’t going to make it go away. It’s vital that more research is carried out to determine causality and to find therapies that work for long-haulers.