Viral Infections

COVID-19 Roundup: Antiviral Pill, Age and Antibody Response, Holiday Precautions

Oral Antiviral Pill1

A new antiviral medication, Paxlovid, was 89% effective in reducing hospital admissions and death in patients with COVID-19 who were at high-risk of severe disease, according to the manufacturer, Pfizer.

Paxlovid, a combination of PF-07321332 and ritonavir, is the second oral antiviral medication to seek approval from regulatory health agencies. Molnupiravir, another antiviral medication, was recently approved in the United Kingdom.

Included in the study were 1219 patients that were randomly assigned to receive Paxlovid or a placebo orally every 12 hours for 5 days. For patients who received Paxlovid within 3 days of symptom onset, hospitalization had occurred in 0.8% (3 of 389) of patients, compared with 7% (27 of 385) of those who had received placebo. There were no deaths among the Paxlovid group and 7 deaths among the placebo group.

Similarly, in those who had received Paxlovid within 5 days of symptom onset, hospitalization occurred in 1% (6 of 607) of the Paxlovid group, compared with 6.7% (42 of 612) of the placebo group. While there were no deaths among the Paxlovid group, there were 10 deaths among the placebo group. 

Age and Antibody Response2

Individuals aged 50 years or older who have been infected with COVID-19 but were not hospitalized may have a greater antibody response than those who were similarly infected but aged younger than 50 years. Antibodies were present in this patient population for 16 weeks after diagnosis.

Originally intending to measure whether natural infection or vaccination led to greater antibody levels in this patient population, the study included 32 adults from Canada who were not hospitalized but were diagnosed with COVID-19 through a polymerase chain reaction (PCR) test. 

“But what’s even more interesting,” said study author Jean-François Masson of the study results in a press release3, “is that we have samples from an individual younger than 49 whose infection didn’t produce antibodies inhibiting spike-ACE-2 interaction, unlike vaccination. This suggests that vaccination increases protection against the Delta variant among people previously infected by the native strain.”

COVID-19 and Holiday Celebrations4

A recent survey revealed that adults in the United States plan to take precautions when gathering for the 2021 holiday season.

Approximately half of respondents will ask guests to wear masks when gathering. This is a decrease from the 2020 holiday season, in which 67% of respondents asked guests to wear masks.

In addition, approximately 75% of respondents will likely celebrate with members of their household. Half of respondents plan to ask about guests’ vaccinations status, and 46% of respondents will require a negative COVID-19 test from their unvaccinated guests before gathering.



  1. Pfizer’s novel COVID-19 oral antiviral treatment candidate reduced risk of hospitalization or death by 89% in interim analysis of phase 2/3 EPIC-HR study. News release. Pfizer; November 5, 2021. Accessed November 15, 2021.
  2. Jodaylami MH, Djaïleb A, Ricard P, et al. Cross-reactivity of antibodies from non-hospitalized COVID-19 positive individuals against the native, B.1.351, B.1.617.2, and P.1 SARS-CoV-2 spike proteins. Sci Rep. 2021;11(1):21601. doi:10.1038/s41598-021-00844-z
  3. COVID-19: the older you are, the more antibodies you have. News release. University of Montreal; November 8, 2021. Accessed November 15, 2021.
  4. Survey finds most Americans will still use COVID precautions this holiday season. News release. The Ohio State University; November 15, 2021. Accessed November 15, 2021.