RIO DE JANEIRO, BRAZIL – Covid-19 symptoms can vary significantly depending on the variant of the Sars-CoV2 virus responsible for the infection, alerts a study from Kings College London, released this month.
According to the study, headache, sore throat and nasal discharge are the symptoms most commonly associated with the Delta variant (originally detected in India), which is now prevalent in the UK. These symptoms were not common in the first wave of the disease, when the Alpha variant (from the UK itself) was predominant.
In Brazil, although there is no similar study, frontline doctors also report a change in the main symptoms of the disease at the start of the pandemic, when the B.1.1.33 and B.1.1.28 variants predominated, and now, when the Manaus variant, Gamma (P.1), prevails.
According to Brazilian reports, the symptoms associated with Gamma are similar to those of the Indian variant: headache, sore throat, and nasal discharge. In other words, something very similar to a heavy cold.
“Covid is different now, more like a severe cold,” summarized Kings College Professor of Genetic Epidemiology Tim Spector, lead author of the British study, “People think they have a mere seasonal cold and keep going out, going to parties. It is important for people to bear in mind that the main symptoms related to Covid have changed since May. Now, the main symptom is headache, followed by sore throat, runny nose, and fever.”
Until now, when the Alpha variant was predominant, the main Covid symptoms, according to British health officials were, in this order: fever, cough, and loss of smell or taste. The recommendation was for anyone with at least one of these symptoms to be tested for Covid. However, now the Indian variant accounts for 90% of cases among Britons.
The mapping of symptoms in the UK has been ongoing since March last year through an app, called Zoe, in which patients report their symptoms. There are now over 4 million reports. The data analyzed by the app shows that a cough was the most common symptom at the start of the pandemic, with 46% of patients reporting the symptom. It has now been surpassed by headache (66%), sore throat (53%), runny nose (49%), and fever (42%).
The Indian variant, it is now known, is at least 40% more transmissible than the Alpha and poses twice the risk of hospitalization. In addition, the available vaccines are somewhat less effective, particularly after only one dose.
Although virtually all elderly people are vaccinated in the UK, a proportion of young adults are still partially vaccinated or not at all. In total, 2/3 of young people are not yet fully protected.
Situation in Brazil
A study conducted in Brazil last year listed the most common symptoms among Brazilians. The survey conducted by the Federal University of Pelotas (UFPel) involved 31,869 people in all states. Among the most common symptoms were headache, changes in smell and taste, fever, cough, and body aches. However, the study has not been redone this year, to consider the prevalence of the Gamma variant.
“The number of strains circulating in the country is very high. There were over 3,000 strains in the last survey,” explained virologist Paola Cristina Resende, a researcher at the Fiocruz Genomics Network, which maps the dispersion of variants in Brazil.
“But our focus is the so-called variants of concern, i.e., those with greater transmission capacity, such as the P1 Gamma, the B.1.7 Alpha, the B.1.1.351 Beta, and the B.1.617.2 Delta. We believe that, when competing with other variants, the P.1 is performing better, which is why it is still predominant in Brazil.”
Most importantly, people should not expose themselves and be tested for Covid-19 when they experience symptoms, according to the experts. Until vaccination advances further, wearing masks and social distancing are the only forms of protection.
First and second wave
According to virologist Fernando Spilki, from Feevale University in Rio Grande do Sul, in terms of symptoms, the main difference between the first and second wave of the pandemic in Brazil was precisely the emergence of coryza. “Last year, when patients developed coryza, they could virtually rule out Covid,” says Spilki.
“The problem is that individuals presenting coryza, a cold, tend to expose themselves more, they won’t protect themselves adequately.”
Fiocruz’s pulmonologist Margareth Dalcolmo has also noticed the difference. “I’ve seen many people with problems in the upper airways, like sore throats and coryza, as if it were some other virus.”