Virus World

A look at how the two authorized vaccines stack up against one another on a host of factors, including efficacy and safety. In an ideal world, a pandemic vaccine could be delivered in a single shot, so supplies could be stretched to cover a lot of people. It would trigger no side effect more significant than a sore arm. And it would be easy to ship and store. Unfortunately, this is not an ideal world — not yet, anyway.  For now, the good news is that the United States has two Covid-19 vaccines that have been shown to be highly effective.  What follows is a head-to-head comparison of the ones developed by Pfizer and its partner, BioNTech, and by Moderna. Note that the chances of most individuals being able to “pick” one or the other are slim to none, especially in the initial rollout. The vaccine available is the one you’ll get. 

Target population

The Pfizer emergency use authorization is for people aged 16 and older. Moderna’s is for people 18 and older, though the company has recently begun testing its vaccine in 12- to 17-year-olds.

Vaccine efficacy 

Both vaccines have shown astonishing — and essentially equivalent — degrees of efficacy, at least in the early stages after vaccination. How they stack up over the long term remains to be seen.  The Pfizer vaccine showed efficacy of 95% at preventing symptomatic Covid infection, measured starting from seven days after the second dose was administered. The vaccine appeared to be more or less equally protective across age groups and racial and ethnic groups.  The Moderna vaccine was 94.1% effective at preventing symptomatic Covid-19, measured starting from 14 days after the second dose. The vaccine’s efficacy appeared to be slightly lower in people 65 and older, but during a presentation to the Food and Drug Administration’s advisory committee the company explained that the numbers could have been influenced by the fact there were few cases in that age group in the trial. The vaccine appeared to be equally effective across different ethnic and racial groups. Both vaccines seemed to reduce the risk of severe Covid disease. It’s not yet known if either prevents asymptomatic infection with the SARS-CoV-2 virus. Nor is it known if vaccinated people can transmit the virus if they do become infected but don’t show symptoms.

Number of doses/amounts of vaccine per dose

Both the Moderna and the Pfizer/BioNTech vaccines require two shots: a priming dose, followed by a booster shot. The interval between Moderna doses is 28 days; for the Pfizer vaccine, it’s 21 days. Each dose of Pfizer’s contains 30 micrograms of vaccine. Moderna went with a much larger dose of vaccine, 100 micrograms. It means it is using a little more than three times as much vaccine per person as Pfizer is. And yet, they aren’t getting better results.....

CDC Data on vaccine adminstration (updated daily):

https://covid.cdc.gov/covid-data-tracker/#vaccinations

Primate centers band together for study rejected by Operation Warp Speed. Primate researchers in the United States have banded together in a push for an ambitious monkey study that would do head-to-head comparisons of the leading COVID-19 vaccine candidates. Although 10 candidates are already undergoing large-scale tests in people, proponents of the monkey plan say those clinical trials may not deliver the comprehensive data needed to choose the safest and most effective vaccines. The comparison trial in monkeys, in contrast, could shed light in a matter of weeks on how the candidates stack up on measures including potential side effects, the strength of immune responses they trigger, and how well they protect against infection and disease. “We should take a cold, hard look at all of the data and ask ourselves, ‘What appears to work best?’” says Nancy Haigwood, who directs the Oregon National Primate Research Center and is a key advocate for the comparative monkey study.

The proposed monkey vaccine comparison faces hurdles: It would add to the pressure on the dwindling U.S. supply of research monkeys, potentially delaying research on other diseases, and it does not yet have funding. Haigwood says she expected the U.S. government would gladly support the effort, which would cost an estimated $10 million, compared with the $10 billion the Trump administration’s Operation Warp Speed has already devoted to a COVID-19 vaccine push. But facing a lack of interest by current Warp Speed officials, Haigwood and colleagues at the six other national primate research centers are now turning to the National Institutes of Health (NIH) for support. Most developers of the vaccine candidates in efficacy trials have already published how well each works in monkeys against a “challenge” with SARS-CoV-2—a deliberate exposure to the pandemic coronavirus that causes COVID-19. But the details of how the experiments were conducted and the ways the results were analyzed differ so profoundly that immunologist John Moore of Weill Cornell Medicine says he can’t make sense of how the candidates compare. “It’s comparing apples to oranges and bananas,” says Moore, who has co-authored a review, on preprint.org, that compares the various monkey studies. 

The human vaccine trials, for their part, are likely to yield only preliminary signals of efficacy over the next few months, not clear-cut evidence that one or more is safe and protects people. “We’re going to get data dribbling in from clinical trials,” says Haigwood, a veteran AIDS vaccine researcher. The data from the many human trials, some in multiple countries, will also be tough to compare. Jay Rappaport, who heads the Tulane National Primate Research Center, notes the trial populations differ and are infected by different variants of SARS-CoV-2. In addition, the human trials—as with the monkey experiments—often use different assays to measure immune responses. “There’s so much variation in the primate studies, but there’s even more variation in the human studies,” Rappaport says. In contrast to the human trials that must wait for enough participants to become naturally infected to gauge a vaccine’s worth, Haigwood says, monkey challenge studies could deliver definitive results quickly. She says the monkey comparison could start as soon as this month and would require only about 6 weeks to vaccinate animals, challenge them, and assess their immune responses and levels of protection...