How alarming are these covid-19 vaccine scares?5 min read . Updated: 21 Jan 2021, 12:59 AM IST
- Any new vaccine could have long-term risks, but most vaccine-related side effects tend to occur within the first two months of an inoculation
Sam Fazeli, a Bloomberg Opinion contributor who covers the pharmaceutical industry for Bloomberg Intelligence, answered questions about vaccine safety after a rash of possible allergic reactions to Moderna Inc.’s Covid-19 vaccine in San Diego prompted a medical expert to recommend withholding some shots from the same batch. This follows reports from Norway earlier in the month of a greater incidence of mortality among elderly who received the Covid-19 shot developed by Pfzer Inc. and BioNTech SE. The conversation has been edited and condensed.
The Moderna vaccine news out of California and Pfizer-BioNTech mortality findings in Norway raised alarms, at least at first blush, and Moderna shares took a hit. How concerning are these things?
It is absolutely vital that side effects and issues related to any vaccine or drug are followed closely. That’s especially so in the case of Covid-19 vaccines, considering that the scale and speed of inoculations far exceeds anything in the history of modern medicine. It is also natural that there should be an abundance of caution as the vaccines are rolled out. But it’s equally important that any issues are dealt with sensitively and sensibly, given how much is riding on the success of the vaccination program. In the case of the deaths in Norway, the authorities should have first looked into the possibility that the high number of deaths per vaccinated subject — about 1 person per 1,000 — was a coincidence or linked to the use of the vaccine in individuals with other serious health conditions who would not normally be candidates for any vaccine.
A quick comparison with the U.S. suggests there is something else going on. Out of 14 million vaccinations, the U.S. Centers for Disease Control and Prevention says it received reports of 44 potential vaccine-related deaths as of Jan. 15, none of which have yet been directly linked to the shot but occurred some time after a dose. This indicates the Norway statistics are skewed. The situation with the allergic reactions in California is different. We know that these vaccines can cause an allergic reaction. The CDC's vaccine safety database has 63 reports of allergic reactions to Covid-19 vaccines, five of which were after the Moderna shot. While that data doesn’t appear to include the most recent incidents in San Diego yet, it’s entirely possible that the cluster of reactions there was a coincidence. But it’s important that the public know that there is a system in place that reviews and assesses these issues, which they need to trust. In the case of San Diego, Moderna is working with the CDC, Food and Drug Administration and California officials to monitor and better understand the situation. While withholding the rest of the Moderna batch is probably prudent, there don’t appear to be any further reactions, and there’s nothing to suggest the vaccine in general is a danger.
The Moderna and Pfizer vaccines use similar technology. What's the safety data on them?
As noted above, the CDC's database, which is updated every Friday, includes all of the side effects that are reported to the agency. Anyone can access the data and analyze it. Of interest to me are cases of Bell's palsy occurring in connection with the Pfizer-BioNTech trial, and thrombocytopenia — abnormally low platelet levels — which can happen after a strong immune reaction. So far, 41 cases of “facial paralysis" and three cases of thrombocytopenia have been reported. Again, in the context of 14 million vaccinations, these numbers, so far, are very low. Other side effects of the two vaccines are the usual ones expected after a vaccination: fever, aches and chills.
Are there risks related to these new vaccines that could manifest over time?
Any new vaccine could have long-term risks, but most vaccine-related side effects tend to occur within the first two months of an inoculation. In general, the risks of vaccines are extremely low relative to the benefits that they bring. Consider polio vaccines as an example, which can lead to rare cases of “paralytic poliomyelitis" (or polio-like paralysis caused by the vaccine itself) at rates of about one per 3 million doses. Compare this with the 1952 polio outbreak in the U.S., which led to close to 58,000 infections and 3,000 deaths. And remember, because of mass vaccinations, polio has not been seen in the U.S. since the 1970s. That said, it’s important to note that when we are dealing with vaccinations at such a large scale, there will be incidences of illness or death that may appear to be related to the vaccine. For example, in 2018, 655,381 people died of heart attacks in the U.S., according to the CDC, or nearly 1,800 per day. It’s likely that some people will have a heart attack the day of or soon after their vaccine doses by sheer coincidence. The National Cancer Institute estimates that there were about 1.8 million cancer diagnoses in the U.S. in 2020. Assuming a similar number in 2021, many people will be diagnosed with cancer some time after receiving their doses of Covid-19 vaccine. The key is to look for excess rates of disease, and this takes time. Rushing out with declarations that a dose of Covid-19 vaccine caused this or that issue is plain wrong.
What about other types of Covid vaccines?
The only other Covid-19 vaccine that has been used in mass vaccinations is the one from AstraZeneca-Oxford University, almost entirely in the U.K. There have been no reports of issues with that vaccine so far. Its acute side effects are similar to those of Pfizer-BioNTech and Moderna. There has not been any indication of allergic reactions to the Astra vaccine.
How is safety tested to begin with? How confident can we be in the bar regulators set?
The first step is to ask for large numbers of people to be included in late-stage phase III trials. Pfizer and BioNTech had 44,000 and Moderna 30,000 in their U.S. trials. AstraZeneca and Johnson & Johnson are at the same levels with their trials. With half of these people getting vaccinated, there will be more than 70,000 people who have received the vaccine, especially because some who were on placebo will now be offered the vaccine. These people are essentially under a safety microscope, and as time passes more and more data will be collected. Then there is the aformentioned vaccine safety database maintained by the CDC, which is available to anyone to look at.
What does a real problem with a vaccine look like?
Neurological side effects, such as seizures or Guillain-Barre syndrome, have been seen with vaccines. Health-care professionals are highly tuned to look for these should they occur, and developers would look to change something in the process or restrict the vaccine to a certain group of people as they seek to reduce risks. The worst type of side effect is one that you cannot monitor closely or explain. So far we have not seen anything like that.
This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.