Patients with SARS-CoV-2 alpha variant do not carry more virus in upper respiratory tract
Click Here to Manage Email Alerts
Patients with the alpha variant of SARS-CoV-2 do not carry more virus in their upper respiratory tract despite increased transmissibility, according to data presented at the World Microbe Forum.
“The increase in B.1.1.7 — now called the alpha — variant toward the end of February and the way it displaced the previous circulating SARS-CoV-2 variants prompted us to wonder if high viral loads in the upper respiratory tract specimens contributed to the increase in transmissibility,” Heba Mostafa, MBBCh, PhD, assistant professor of pathology and director of molecular virology at the Johns Hopkins School of Medicine, told Healio. “A key variable that we tried to control for as we conducted our study was the days to the onset of symptoms as it was shown that the viral loads differ based on the course of the infection.”
Mostafa and colleagues evaluated if patients had higher viral loads and, consequently, increased shedding and transmissibility if they were infected with the alpha and beta (B.1.351) variants. According to the study, the researchers used whole genome sequencing to identify the variants and then compared 134 variant samples with 126 control samples.
Overall, the study showed that there was no increase in the viral loads in samples collected from patients infected with the alpha variant when compared with the viral loads in samples from patients infected with the prevalent lineages before the alpha variant predominance. Mostafa added that although the study initially set out to assess the alpha and beta variants, there were very few patients with the beta variant available, preventing proper assessment.
According to the researchers, while analyzing viral loads based on patients ages, they found that the control group had a significantly lower mean Ct value compared with the alpha and beta variants group (P = .0062). This difference disappeared as the data were correlated to the time from symptom onset, Mostafa added.
A clinical chart review compared disease severity and outcomes after infection with the variants compared with the control group. The researchers reviewed a total of 124 charts of patients infected with the two variants of concern and a total of 102 charts of patients infected with previous lineages. Overall, the researchers found an increase in symptomatic infections in the group infected by the variants compared with the control group (95.2 % vs. 81.4%; P = .002), as well as an increase in hospitalization rates (20.2% vs. 12.7%). Although it is still not clear why the variants are more transmissible, Mostafa said that based on the group’s mathematical model, the higher likelihood of symptoms with the alpha variant could explain the population level increase in transmission.
“Our main message is that in our cohort, we didn’t notice that patients with the alpha variant carry more virus in their upper respiratory tract,” Mostafa said.
Collapse
Luo CH, et al. SARS-CoV-2 variants of concern B.1.1.7 and B.1.351 are not associated with higher viral loads. Presented at: World Microbe Forum. June 20-23, 2021 (virtual meeting).
Read more about
Click Here to Manage Email Alerts