BCSnob wrote:



If one counts the estimated 11.2M fully vaccinated people, then the percentage of the population with immunity increases to 38%.

BCSnob wrote:

The dropping cases is very good news; it means people have been careful about reducing their exposure risk.

N Engl J Med 2020; 383:2603-2615 wrote:

Efficacy

The first primary end point was the efficacy of BNT162b2 against confirmed Covid-19 with onset at least 7 days after the second dose in participants who had been without serologic or virologic evidence of SARS-CoV-2 infection up to 7 days after the second dose; the second primary end point was efficacy in participants with and participants without evidence of prior infection. Confirmed Covid-19 was defined according to the Food and Drug Administration (FDA) criteria as the presence of at least one of the following symptoms: fever, new or increased cough, new or increased shortness of breath, chills, new or increased muscle pain, new loss of taste or smell, sore throat, diarrhea, or vomiting, combined with a respiratory specimen obtained during the symptomatic period or within 4 days before or after it that was positive for SARS-CoV-2 by nucleic acid amplification–based testing, either at the central laboratory or at a local testing facility (using a protocol-defined acceptable test).

Major secondary end points included the efficacy of BNT162b2 against severe Covid-19. Severe Covid-19 is defined by the FDA as confirmed Covid-19 with one of the following additional features: clinical signs at rest that are indicative of severe systemic illness; respiratory failure; evidence of shock; significant acute renal, hepatic, or neurologic dysfunction; admission to an intensive care unit; or death. Details are provided in the protocol.

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N Engl J Med 2021; 384:403-416 wrote:

Efficacy Assessments

The primary end point was the efficacy of the mRNA-1273 vaccine in preventing a first occurrence of symptomatic Covid-19 with onset at least 14?days after the second injection in the per-protocol population, among participants who were seronegative at baseline. End points were judged by an independent adjudication committee that was unaware of group assignment. Covid-19 cases were defined as occurring in participants who had at least two of the following symptoms: fever (temperature ?38°C), chills, myalgia, headache, sore throat, or new olfactory or taste disorder, or as occurring in those who had at least one respiratory sign or symptom (including cough, shortness of breath, or clinical or radiographic evidence of pneumonia) and at least one nasopharyngeal swab, nasal swab, or saliva sample (or respiratory sample, if the participant was hospitalized) that was positive for SARS-CoV-2 by reverse-transcriptase–polymerase-chain-reaction (RT-PCR) test.

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Quote:

’We could be approaching herd immunity’: Epidemiologist on coronavirus pandemic

As the seven-day average of newly confirmed COVID-19 cases in the U.S. dramatically declines, down about 66% from a month ago, Suzanne Judd, an epidemiologist at the University of Alabama at Birmingham School of Public Health, says it’s “possible” we’re approaching herd immunity.

Judd points to a Columbia University study that estimates the number of active COVID-19 cases in the U.S. could be 10 times the number confirmed through testing. The study, published by NPR ahead of peer review, suggests that as of the end of January, more than a third of the U.S. population had already been infected with coronavirus.

“You add the findings from the Columbia study to the number of vaccinations that have been rolling out, and it’s possible that we could be approaching herd immunity,” Judd told Yahoo Finance Live. “We should know within the next two or three months if this trend holds, but this is definitely the most positive news we have seen in a long time.”

Quote:

Active COVID Cases May Be Ten Times Official Count: Study


The number of active COVID-19 cases in the United States is roughly ten times higher than the number of confirmed cases on any given day, according to a computer model by Columbia University Mailman School of Public Health scientists. Since the start of the pandemic, an estimated one-third of the U.S. population has already been infected, with numbers five times that of the official count.

Jeffrey Shaman, PhD, a professor of environmental health sciences known for his COVID-19 projections, led the research, based on case numbers and anonymized cellphone location data to estimate population mixing. The findings appear ahead of peer review in a report by NPR.