COVID-19: Evidence continues to mount on immunity in unexposed & seronegative individuals

In May, I wrote about a number of studies which showed T-cell reactivity to SARS-CoV-2 in individuals who were not previously exposed to the virus (eg in samples obtained in 2015). The past several weeks have seen mounting evidence from independent researchers bolstering the case that a substantial proportion of the population already possess some…

CDC releases estimates for COVID-19 fatality rates

At long last, the CDC has finally released comprehensive estimates regarding the COVID-19 pandemic under five different scenarios meant to help guide policy going forward. The scenarios include the CDC’s “current best estimate,” and all are based on information up to April 29th. Some key points: The CDC estimates that the fatality rate for COVID-19…

COVID-19: Coronavirus immunity without antibodies? The plot thickens (again!)

So do antibodies developed do to prior exposure to other coronaviruses offer protection against SARS-CoV-2? Paper #1: In 40-60% of a group of individuals not exposed to SARS-CoV-2 (samples collected between 2015-18), T helper cells were reactive to SARS-CoV-2; as the authors note, the most plausible explanation is cross-reactivity due to previous infection with endemic,…

COVID-19: Coronavirus immunity without antibodies? The plot thickens

I recently wrote about a paper showing robust T helper cell reactivity to SARS-CoV-2 in a group of recovered patients as well as the tantalizing finding that 40-60% of unexposed individuals (samples obtained 2015-18) showed cross-reactivity to SARS-CoV-2, suggesting that exposure to circulating coronaviruses responsible for the common cold could be protective against SARS-CoV-2. Meanwhile,…

COVID-19: Could exposure to ‘common cold’ coronaviruses offer some protection against SARS-CoV-2?

Although not all that surprising in hindsight, the results of a paper recently published in Cell are nevertheless stunning: 40-60% of a group of individuals not exposed to SARS-CoV-2 were found to have T helper cells that were reactive to SARS-CoV-2. The article summary: “Understanding adaptive immunity to SARS-CoV-2 is important for vaccine development, interpreting…

COVID-19: How unusual is the age distribution of deaths?

The University of Oxford’s Centre for Evidence-Based Medicine recently compared the age distribution of COVID-19 deaths with deaths from the 2009 flu pandemic (which is estimated to have killed 150,000-575,000 worldwide).1 One remarkable aspect of the 2009 flu was that it resulted in disproportionately greater mortality among younger and generally healthier people than in a…

COVID-19: Have high hospitalization rates made things worse?

While the 2002-2004 SARS coronavirus typically led to more severe clinical presentation than seen with COVID-19 (14-20% of patients required ventilatory support, and the case fatality rate was 9.2% compared to 4.1% and 5.6% respectively for COVID-19),1 this actually contributed to effective containment of the outbreak. High rates of nosocomial transmission and severity of presentation…

COVID-19: Oxford’s Centre for Evidence-Based Medicine estimates global infection fatality rate of 0.29%

The University of Oxford’s Centre for Evidence-Based Medicine offers an extensive assessment of COVID-19 mortality and infection data in its article on Global Covid-19 Case Fatality Rates, updated daily. “Comparison with Swine Flu The overall case fatality rate as of 16 July 2009 (10 weeks after the first international alert) with pandemic H1N1 influenza varied…

COVID-19: Did the Spanish Flu kill “an estimated 2 to 3 percent of those infected”?

Within the past few weeks, as the COVID-19 pandemic spread across the world, commenters in news media have propagated a meme that’s now firmly embedded in the public consciousness. It’s best summed up in an article in Vox that’s typical of the trend, “Did the coronavirus get more deadly? The death rate, explained.”1 The Vox…

COVID-19: Mathematical models in the face of uncertainty

A study recently released by Imperial College London has been heavily reported in the media; the authors estimate that in the absence of mitigation, COVID-19 could claim the lives of 510,000 people in Great Britain and 2.2 million people in the United States by the end of August.1 A collaborative study overseen by Columbia University…