What the Covid-19 Vaccines Are and Are Not Claimed to Do

There has been a lot of noise regarding the news reports that Congressman Stephen Lynch tested positive even though he had received both doses of the Pfizer vaccine. There is nothing newsworthy there — here‘s why.

Despite some clumsy reporting claiming that Rep. Lynch tested positive for Covid-19, he did not. He tested positive for the SARS-CoV-2 virus. Since he doesn’t have symptoms, he does not have Covid-19 (yet?). The distinction is huge when we’re talking about vaccines.

The vaccines are intended to prevent, or at least reduce, the symptoms of Covid-19 disease. They are not required to prevent contracting the virus, and the trials were and are not looking to see who contracted the virus. The big goal is to keep people from getting so sick that they end up in the hospital, in the ICU, or dead.

What three Phase III studies count as a case of Covid-19
Pfizer / BioNTech	“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.”
Moderna	“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).”
Johnson & Johnson / Janssen	Moderate disease: “Evidence of pneumonia; deep vein thrombosis; difficulty breathing; abnormal oxygen saturation or a respiratory rate equal to or greater than 20; or two or more signs or symptoms suggestive of COVID-19, such as cough, sore throat, fever, or chills.” Severe disease: “Evidence of clinical signs at rest indicative of severe systemic illness, respiratory failure, shock, significant organ dysfunction, hospital intensive care unit admission or death.”

What three Phase III studies count as a case of Covid-19

Pfizer / BioNTech

“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.”

Moderna

“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).”

Johnson & Johnson / Janssen

Moderate disease:
“Evidence of pneumonia; deep vein thrombosis; difficulty breathing; abnormal oxygen saturation or a respiratory rate equal to or greater than 20; or two or more signs or symptoms suggestive of COVID-19, such as cough, sore throat, fever, or chills.”

Severe disease:
“Evidence of clinical signs at rest indicative of severe systemic illness, respiratory failure, shock, significant organ dysfunction, hospital intensive care unit admission or death.”

Most people who get Covid-19 disease don’t get it bad enough to need to go to the hospital. So if the vaccine trials were counting on hospitalizations and deaths to give a solid picture of the preventative power of the vaccine, it would take a long time to collect enough cases. The vaccine trials looked at something that would be more common: symptoms of Covid-19, even the minor ones. The logic is that if you don’t get the minor symptoms, you’re not going to end up in the hospital, or dead.

So the efficacy numbers reported in the press are for preventing people from getting symptoms. The table shows what each of three Phase III trials mean by “symptoms.” In each trial, these symptoms had to be backed up by a positive test for SARS-CoV-2 virus in order to count.

None of the vaccine trials, at least so far, has been designed to study the efficacy against catching the SARS-CoV-2 virus nor, perhaps more importantly, the efficacy against spreading the virus if it is caught. It’s quite possible that some, maybe most, vaccinated people would become silent carriers of the virus should they get exposed. We don’t know.

Until we get to the point where everyone who wants a vaccine has gotten it, we’ll probably be wearing masks and social distancing. When that will be is anybody’s guess. Even then, the virus is likely to be here for keeps, somewhat like influenza is.

Oh, and something else that the trials aren’t looking for: significant lung damage in reportedly 70% or so of people who got the virus but no symptoms. Will the vaccines help prevent that? I guess we’ll have to wait and see.

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What the Covid-19 Vaccines Are and Are Not Claimed to Do

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