Antibodies in blood samples of individuals who experienced breakthrough COVID-19 infections were as much as 1,000 percent more effective than the antibodies generated two weeks after the second Pfizer vaccine dose, according to a small study's findings published Dec. 16 in the Journal of the American Medical Association.

COVID-19 cases are surging across the U.S. ahead of Christmas, sparking the cancellation of sporting events and a growing list of hospitals postponing nonessential surgeries — both a reminder of last year's holiday surge and a sign that the next several weeks will determine the pandemic's trajectory for the rest of the winter months. 

New daily COVID-19 cases have increased more than 200 percent over the last two weeks in two states and Washington, D.C., according to local and state data tracked by The New York Times.

Twelve states reported high or moderate flu activity for the week ending Dec. 11, according to data from the CDC's FluView report published Dec. 17. 

The nation's seven-day average for COVID-19 cases, deaths and hospitalizations increased slightly last week, according to the CDC's COVID data tracker weekly review published Dec. 17.

We celebrate the anniversary of the first COVID-19 vaccines this winter—and progress in controlling the virus. With vaccines readily available and recommended for everyone age 5 years and older, more people are traveling and including travel in their holiday plans.

As new variants emerge, fully vaccinated people testing positive for COVID-19 won't be uncommon, Vin Gupta, MD, said Dec. 16 on the Today show.

At least four states have set COVID-19 records over the last week.

COVID-19 cases nationwide are surging as delta remains the dominant strain and the threat of omicron looms. 

More Americans are concerned about personally contracting cancer or heart disease than COVID-19, according to Gallup poll findings published Dec. 16. 

The omicron coronavirus variant infects and multiplies 70 times faster in the human bronchus than delta and the original strain, according to preliminary findings from researchers at the University of Hong Kong in China. 

At Houston Methodist, 32 percent of all COVID-19 tests for symptomatic patients are now omicron — an increase from 13 percent four days prior, according to new data sent to Becker's in a Dec. 15 news release.

More research is needed to understand the global "coronaviral universe" and use that information to develop vaccines that are broadly protective against coronaviruses, three leaders from the National Institutes of Health wrote in a Dec. 15 op-ed published in The New England Journal of Medicine. 

Rhode Island is seeing the highest average rate of daily COVID-19 cases per 100,000 people in the nation, with higher rates than all other states as well as every major U.S. region, according to state and local health agency data cited by The New York Times.

The omicron variant is spreading faster than any other COVID-19 variant, the World Health Organization warned during a Dec. 14 news conference. 

More than 50 million people in the U.S. have fallen ill with COVID-19 since the start of the pandemic in March 2020, and nearly 800,000 Americans have died as of Dec. 14 — one year after the first U.S. COVID-19 vaccine was administered — according to data from Johns Hopkins University Coronavirus Resource Center. 

Genomic surveillance data indicates the omicron COVID-19 variant accounts for about 3 percent of new U.S. cases, CDC Director Rochelle Walensky, MD, told NBC's Today on Dec. 14. 

Below, states are listed by mask policies, as reported by The New York Times.

Instead of only using virus case counts, policymakers should tie pandemic guidance to COVID-19 hospitalization metrics, especially in highly vaccinated areas, Monica Gandhi, MD, and Dr. Leslie Bienen wrote in an op-ed published Dec. 11 by The New York Times.

Between 25 percent to 43 percent of fully vaccinated patients at major Massachusetts hospitals tested positive for COVID-19 in the week ending Dec. 10, WBUR reports.