https://www.nature.com/articles/s41586-020-2918-0

Estimating the size and infection severity of the SARS-CoV-2 epidemic is made challenging by inconsistencies in available data. The number of COVID-19 deaths is often used as a key indicator for the epidemic size, but observed deaths represent only a minority of all infections^1,2.

Additionally, the heterogeneous burden in nursing homes and variable reporting of deaths in elderly individuals can hamper direct comparisons across countries of the underlying level of transmission and mortality rates³. Here we use age-specific COVID-19 death data from 45 countries and the results of 22 seroprevalence studies to investigate the consistency of infection and fatality patterns across multiple countries.

We find that the age distribution of deaths in younger age groups (<65 years) is very consistent across different settings and demonstrate how this data can provide robust estimates of the share of the population that has been infected.

.... As more families make the jump back to group day care this fall in an attempt to restart lives and careers, many parents, pediatricians and care operators are finding that new, pandemic-driven rules offer a much-needed layer of safety but also seem incompatible with the germy reality of childhood.

They stem largely from coronavirus guidelines issued by the Centers for Disease Control and Prevention lowering the fever threshold, disqualifying even a single bout of diarrhea or vomiting and making sniffles suspect in group settings.

But the guidelines don’t take into account that young children are prone to catching the common viral infections that help build up their immune systems, or that seasonal allergies, crying, even teething and normal playground exertion can prompt a COVID-19-like symptom.

And the price parents and kids pay for such symptoms — which could easily signal either a happy, healthy toddler, or a lurking case of the disease that has now killed more than 230,000 people in the U.S. — is now a dayslong disruption. ...uilt over neglecting work.

As rapid coronavirus tests are becoming more widely available, delivering results in minutes for patients in doctor's offices, nursing homes, schools and even the White House, officials warn of a significant undercount, blurring the virus's spread nationally and in communities where such tests are more commonly used.

Public health officials say that antigen tests, which are faster than polymerase chain reaction (P.C.R.) tests but less able to detect low levels of the virus, are an important tool for limiting the spread of the coronavirus. But they caution that with inconsistent public reporting, the case undercount may worsen as more “point-of-care” antigen tests, as well as D.I.Y. and home test kits, come on the market.

“We want to be sure that we’re not now saying, ‘there’s no disease,’ when there is lots of disease. All that’s happened is that the science with which we identify it has evolved,” said Janet Hamilton, the executive director of the Council of State and Territorial Epidemiologists, the group that helps the Centers for Disease Control and Prevention define cases of the coronavirus....