Model predicts natural COVID-19 immunity wanes fast, re-infection likely
Reinfection from SARS-CoV-2 under endemic conditions will most likely occur at a median of 16 months, according to a modeling study published late last week in The Lancet Microbe.
The researchers looked at the human-infecting coronaviruses SARS-CoV-2, SARS-CoV, MERS-CoV, HCoV-229E, HCoV-OC43, and HCoV-NL63 from Feb 12 to Jun 15, 2020, analyzing about 58 alphacoronavirus, 105 betacoronavirus, 11 deltacoronavirus, and 3 gammacoronavirus genome sequences. They compared peak-infection and reinfection data in endemic scenarios. The method also used antibody optical density data spanning 128 days to 28 years post-infection from 1984 to 2020.
According to the model they derived from the data, reinfection by SARS-CoV-2 under endemic conditions would likely occur from 3 months and 5.1 years after peak antibody response, with a median of 16 months. This is less than half the time for other endemic human-infecting coronaviruses (e.g., HCoV-OC43 was associated with 15 months to 10 years). Even for SARS-CoV, the virus that causes SARS and is closest in time range, the model projected a range of 4 months to 6 years.
“Reinfection can reasonably happen in three months or less,” said lead author Jeffrey Townsend, PhD, in a University of North Carolina (UNC) at Charlotte press release. “Therefore, those who have been naturally infected should get vaccinated. Previous infection alone can offer very little long-term protection against subsequent infections.”
The study author conclude, “Our results caution that reinfection will become increasingly common as pandemic disease transitions into endemic disease.”
Oct 1 Lancet Microb study
Oct 1 UNC at Charlotte press release
Screen time, physical activity linked to youth mental health in pandemic
More screen time and suboptimal physical activity during the pandemic were linked to more mental health difficulties in US children ages 6 to 17, according to a JAMA Network Open study late last week.
The researchers looked at survey data regarding mental health, COVID family impact, and physical activity among 1,000 children from Oct 22 to Nov 2, 2020, with parents filling out all information for those 6 to 10 years and supplemental information for older children. Out of the cohort, 52.7% were boys and 31.6% were not White. Half (50.6%) attended school virtually, 22.2% attended it online, and 27.2% had a hybrid arrangement.
About one in five children (20.9%) had at least 60 minutes of physical activity every day, but 8.4% didn’t reach that benchmark any day of the week (average, 3.9 days). Children also reported an average of 4.4 hours per day of recreational screen time.
After accounting for COVID-19 stressors, more screen time was associated with higher total difficulties among younger and older children (beta coefficients, 0.3 and 0.4, respectively). Engaging in 7 days per week of physical activity compared with 0 was linked with fewer externalizing symptoms (those affecting others) in younger children. In older children, at least 1 day of physical activity was linked with fewer externalizing and internalizing (affecting the child, not others) symptoms.
Behavioral issues and hyperactivity were considered externalizing symptoms, while emotional issues were considered internalizing symptoms. Overall, 13.7% of the children were being evaluated or were diagnosed as having anxiety, 10.4% depression, 15.0% attention-deficit hyperactivity disorder, and 11.4% a behavioral problem.
“Notably, children who were exposed to more pandemic-related stressors engaged in less physical activity and had more screen use than their peers who were less exposed,” the researchers write. “Better health behaviors, in turn, were associated with better mental health, even when accounting for differences in exposure to pandemic-related stressors and demographic factors.”
They added that, while middle schoolers and high schoolers engaged in less physical activity, even 1 day a week of physical activity was associated with better mental health.
Oct 1 JAMA Netw Open study