Virus World

An analysis of four different coronaviruses over an 8-year period demonstrated that they were detected in a limited timeframe, from December to April and May, with a peak during January and February, according to a recent study published in Journal of Infectious Diseases. “This is part of a continuing study in families first designed to examine how the influenza vaccine is working in the community,” Arnold S. Monto, MD, Thomas Francis, Jr. Collegiate Professor of Public Health at the University of Michigan School of Public Health, told Healio. “We have expanded it to look broadly at all respiratory viruses.”

The four coronaviruses in the study are known to cause respiratory infections every year, according to Monto: “We had these data ready to go when the pandemic started.” Acute respiratory infections have been identified in children and adults aged 8 years and older as part of the Household Influenza Vaccine Evaluation study. Researchers obtained specimens from 890 to 1,441 individuals in Michigan, who they followed and contacted weekly in order to obtain information about acute respiratory infections. Specimens were tested for four coronavirus types: OC43, 229E, HKU1 and NL63.

Over the 8-year study period, 993 coronavirus infections were detected. The most common type was OC43 and 229E was the least common. The study showed that the coronaviruses were identified during a limited time period, from December to April/May, with a peak recorded in January or February. The viruses began to diminish in March.

Study Published in J. Infect. Diseases (April 4, 2020):

 https://doi.org/10.1093/infdis/jiaa161

A significant number of infectious diseases display seasonal patterns in their incidence, including human coronaviruses. Betacoronaviruses such as MERS-CoV and SARS-CoV are not thought to be seasonal.

To date, Coronavirus Disease 2019 (COVID-19), caused by SARS-CoV-2, has established significant community spread in cities and regions along a narrow east west distribution roughly along the 30-50o N’ corridor at consistently similar weather patterns consisting of average temperatures of 5-11oC, combined with low specific (3-6 g/kg) and absolute humidity (4-7 g/m3 ). There has been a lack of significant community establishment in expected locations that are based only on population proximity and extensive population interaction through travel.

The distribution of significant community outbreaks along restricted latitude, temperature, and humidity are consistent with the behavior of a seasonal respiratory virus. Additionally, we have proposed a simplified model that shows a zone at increased risk for COVID-19 spread. Using weather modeling, it may be possible to predict the regions most likely to be at higher risk of significant community spread of COVID-19 in the upcoming weeks, allowing for concentration of public health efforts on surveillance and containment.

A new report, sent to the White House science adviser, says the country should not rely on warm weather to stop contagion. The homebound and virus-wary across the Northern Hemisphere, from President Trump to cooped-up schoolchildren, have clung to the possibility that the coronavirus pandemic will fade in hot weather, as some viral diseases do.

But the National Academies of Sciences, Engineering and Medicine, in a public report sent to the White House, has said, in effect: Don’t get your hopes up. After reviewing a variety of research reports, a panel concluded that the studies, of varying quality of evidence, do not offer a basis to believe that summer weather will interfere with the spread of the coronavirus. The pandemic may lessen because of social distancing and other measures, but the evidence so far does not inspire confidence in the benefits of sun and humidity.

The report, sent to Kelvin Droegemeier, director of the Office of Science and Technology Policy at the White House and acting director of the National Science Foundation, was a brief nine-page communication known as a rapid expert consultation. Kristian Andersen, an immunologist at the Scripps Research Translational Institute in California and a member of the Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats at the National Academies, said: “Given current data, we believe that the pandemic likely will not diminish because of summer, and we should be careful not to base policies and strategies around the hope that it will.”

“We might very well see a reduction in spread in the beginning of the summer,” he added, “but we have to be careful not to put that down to a changing climate — it is plausible that such a reduction could be due to other measures put in place.”

Original Report (April 7, 2020):

https://www.nap.edu/read/25771/chapter/1

Toward the end of last year’s flu season — in about the middle of winter — flu experts noticed that the number of infections was not dropping, but picking up. A new virus seemed to be emerging, and it was making many Americans sick.  The virus was a type of H3N2 strain, and it started rapidly spreading among people in the United States before spreading into Europe, Canada, and South America. This put scientists worldwide who are tasked with determining what’s in the yearly flu vaccine on high alert. Did the flu vaccine for the 2019–2020 flu season need to be updated to protect against this new virus strain? The next flu season was still many months away, but it was time to scramble.

“Almost every year there is some kind of challenge,” says Dr. David Wentworth, a leading flu expert and chief of the U.S. Centers for Disease Control and Prevention’s (CDC) Virology, Surveillance, and Diagnosis Branch. “The thing about the flu is you have to be nimble.” One of the trickiest tasks for public health experts worldwide is creating the annual flu vaccine. The number of people who get sick from the flu each year depends largely on how well scientists predict what strains of the flu will be circulating and match them with a successful vaccine. “The flu virus evolves so fast,” says Wentworth. “It’s important to update the vaccine when it changes significantly enough to warrant it.”

The process of identifying the “right” viruses and producing enough flu vaccine for the nation starts with year-round study of flu viruses globally and ends with millions of Americans being vaccinated, the CDC says. While the effectiveness of each year’s flu vaccine can vary, the vaccine still prevents millions of illnesses, tens of thousands of hospitalizations, and thousands of deaths every year in the United States. And this year, the new vaccine does contain a new H3N2 strain. Flu experts worldwide, Wentworth says, are always prepared for the unpredictable. “We get kind of used to it with influenza because there are a lot of curveballs you need to respond to very rapidly,” he says. Wentworth and the CDC’s flu team led Elemental through their process for making this season’s flu vaccine.

How well the flu vaccine works in a given year depends partly on the match between the viruses used to make the vaccine and the viruses spreading among people during a given flu season. That’s why a year ago flu researchers started considering the newer H3N2 strain for this year’s vaccine. In fact, Wentworth and his team are already thinking about the vaccine for the 2020–2021 flu season.