But despite high efficacy rates and the promise of a faster return to normal life, some areas have refused shipments of a particular vaccine, due to concern over what vaccine is the “best” one. The truth is, all three vaccines have undergone intensive clinical testing and a difference of 10 to 20 percentage points isn’t as medically significant as it may seem. It will be much harder for the virus to spread if more people are vaccinated, thus, right now it’s arguably more important to have higher numbers of inoculated individuals. They all work, and there is no need to stress about which one you receive. Supriya Narasimhan, MD, MS, chief of infectious diseases at Santa Clara Valley Medical Center in San Jose, California explains, “To prevent and to protect our most vulnerable subjects, it is important for people to take whatever vaccine they are offered,” stresses Dr. Narasimhan. “Please know that these vaccines have been and are being rigorously studied and are safe and effective.”
What Vaccines Are Available?
A quick recap: COVID-19 vaccines from Pfizer-BioNTech, Moderna, and Janssen (Johnson & Johnson) have emergency use authorization (EUA) from the Food and Drug Administration (FDA). The Pfizer-BioNTech vaccine, the first to get an FDA EUA on December 11, 2020, is a messenger RNA (mRNA) vaccine recommended for anyone age 16 and older (testing is ongoing in kids ages 12 to 15). It reports up to 95% efficacy and the dosage is two shots, 21 days apart. The Moderna vaccine—also an mRNA vaccine—was hot on the heels of Pfizer-BioNTech, getting FDA authorization on December 18. It has an efficacy rate of 94% (86% in the over-65 age group). It’s recommended for ages 18 and up, and is being tested in children ages 12 to 17. If you get the Moderna vaccine, you get two shots, 28 days apart. The most recent COVID-19 vaccine, from Janssen (Johnson & Johnson), secured emergency use approval on February 27, 2021. This one is a carrier (virus vector) vaccine and requires only a single shot. It’s suitable for adults age 18 and older, with testing on children scheduled to start soon. The Johnson & Johnson vaccine has an overall efficacy rate of 66%.
Is There a ‘Best’ Vaccine?
Absolutely not, say experts. And they warn that there’s little point in dwelling on efficacy rates, because that oft-cited percentage is only a very small part of a much bigger picture. “Vaccine efficacy is the term used to describe how well the vaccine translates in protecting individuals in the population from disease,” says Narasimhan. For example, in a population without any vaccination with 100,000 people, where 1% would be expected to become ill with COVID-19, we would expect 1,000 COVID-19 cases, Dr. Narasimhan explains. “However, in that same population of 100,000 people vaccinated with the vaccine of 95% efficacy, we would only expect 50 COVID-19 cases. In other words, of the 1,000 people who would have become ill with COVID-19 without vaccination, the vaccine would have protected 950 of them.” On the face of it, the Pfizer-BioNTech and Moderna vaccines have a significantly higher efficacy rate than the Johnson & Johnson vaccine. But it’s important to remember that the vaccines were tested at different time points in different countries. This means that the test results have been influenced by the presence of variant strains as well as different populations (specifically, the strains that originated in South Africa and Brazil were circulating during testing of the Johnson & Johnson vaccine). “They cannot be compared directly,” Dr. Narasimhan says.
Efficacy vs. Effectiveness
It’s common for efficacy to be confused with effectiveness, but they’re actually different things, says Richard Seidman, MD, MPH, chief medical officer of L.A. Care Health Plan, the largest publicly operated health plan in the country. “Effectiveness measures the ability of a vaccine to prevent outcomes of interest (i.e. inflections, transmission, hospitalization, and death) in the ‘real world’ after approved vaccines are administered to the general population,” Dr. Seidman explains. Because we’re still in the early stages of vaccine rollout, it will be some time before scientists have the data to say with any certainty how “effective” they are. Basically, what matters is that all three of the COVID-19 vaccinations currently authorized for emergency use by the FDA have demonstrated high levels of efficacy. To put the figures into perspective, the flu vaccine reduces the risk of flu illness by between 40% and 60% among the overall population, according to the most recent data from the Centers for Disease Control and Prevention (CDC).
Getting the COVID-19 Vaccine Is a Crucial Step Toward Normalcy
While the current, more favorable COVID-19 numbers are due in part to immunity from previous exposure within the community, or without any symptoms being recognized, maintaining and improving upon this depends on vaccine-derived protection, says Charles Bailey, MD, medical director for infection prevention at Providence Mission Hospital and Providence St. Joseph Hospital in Orange County, California. “The more quickly we limit the number of potential COVID-19 patients (by vaccine-induced immunity), the less time there will be for a variant strain to emerge and circulate while there are still big enough numbers of non-immune patients to sustain spread,” Dr. Bailey explains. The experts agree that the safest and fastest way to end the pandemic is for as many people as possible to get vaccinated as quickly as possible. “The goal is to achieve ‘herd immunity,’ which is when a sufficient percentage of the population becomes immune to COVID-19, either through vaccination or previous infection, to the point that there is a much lower risk for those lacking immunity to become infected,” explains Dr. Seidman. The simple fact is that the longer it takes for a high enough percentage of the population to become immune, the more people will become infected, and some proportion of them will be hospitalized and die of the disease, he adds. “We don’t know yet how long immunity lasts after COVID-19 infection, and we don’t know what percentage of the population needs to be immune before we reach herd immunity—it’s possibly as high as seventy to eighty-five percent,” Dr. Seidman says. “What we do know is that the safest and fastest way to get there and put the pandemic in the rear view mirror is for everyone to get vaccinated as quickly as possible once they are eligible to do so.” The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page. If you have any questions or concerns about the COVID-19 vaccine, speak to your primary care doctor.
