It's been another whiplash week in covid-land, with crushing numbers of hospitalizations and deaths juxtaposed against the first vaccine administrations to healthcare providers and a second vaccine granted Emergency Use Authorization by the FDA followed by a positive vote from the ACIP/CDC. Presumably we will see the Moderna vaccine shipped this week, along with ongoing distribution of the Pfizer vaccine. I won't spend any time detailing the basics of the Moderna vaccine; it is an mRNA vaccine very similar to the Pfizer vaccine and much detail is available at FDA and CDC websites. However, I did want to mention a few nuances.
First, evidence to date is insufficient to compare safety and efficacy of the two vaccines. The study findings were very similar, and given the minor differences in study design it would be improper to consider any head-to-head comparison at this time. Eventually we should know about any significant differences such as duration of immunity.
Note that a good deal of the discussion at the FDA/VRBPAC meeting concerned how to continue the ongoing Pfizer and Moderna trials: ethics and practical considerations of how to manage the placebo recipients in those trials who do have the ability to drop out of further follow up in the trials as well as seek their own antibody testing and immunization. The logistics of continuing a double-blinded crossover design trial (placebo recipients receive vaccine, vaccine recipients receive placebo) are large. Many have advocated continuing with an open-label trial where placebo recipients receive vaccine but agree to continue in some modified follow up within their study.
A few more details about side effects have emerged. As in the Pfizer study, a few people developed Bell's palsy in the Moderna trial, too few to determine if this is above expected rates in the general population or greater in vaccine versus placebo recipients. Also, as in the Pfizer trial a handful of women were pregnant in both groups. These pregnancies are being followed by study investigators.
Of interest are a few cases of facial swelling following vaccine, all in individuals who underwent cosmetic injections in lips and similar areas. Apparently this has been reported with other vaccines such as flu vaccine, as well as with natural viral infections. It appeared these reactions resolved with no permanent sequelae but again are being watched.
In the meantime, a few more healthcare providers have developed anaphylactic-like reactions that may be tied to the Pfizer vaccine, even though this wasn't seen in the clinical trials. Note that a far greater number of people have received vaccine in the past week, over 500,000 in the US, than received vaccine in the trials. Rare events sometimes are noted after approval of any drug or vaccine due to larger numbers of people receiving the product.
I'm hoping I will be called to receive my COVID-19 vaccine soon, but regardless of vaccine status remember we all must continue safe public health practices and promote them to our patients.
Thank you as always for your updates !
a quick question re: the new U.K. variant
Are the CDC or other public health authorities in the US doing whole genome sequencing - do we know if we have cases of this variant in the US already ?
Hello Mike,
Thanks for posing this question, one of many I didn't think I had space to address in the post.
First, everyone should remember that we expect many, many mutations to be seen with SARS-CoV-2. This is typical of all RNA viruses and for coronaviruses in particular. They don't have great "proofreading" for errors in their RNA during replication.
What we know so far about the UK situation is that the country is seeing a rapid rise in new cases and that this new variant has emerged. So, that's an association but not necessarily a cause and effect. It is somewhat biologically plausible that there could be a connection since the mutation does result in changes in the Receptor Binding Domain of the spike protein, so could make it easier to attach to cells. It will require a lot of work with case tracing and testing to determine if this mutant does transmit more easily. However, so far there is no indication that it impacts disease severity.
Specifically with regard to your questions, virus sequencing is ongoing not only in the US but worldwide and has been in place for many months. I certainly wouldn't be surprised to learn that this mutation is already circulating in the US, but nothing reported on that so far.
It will be very important to know whether vaccine-induced antibody neutralizes this new strain; I know Moderna is actively testing this against new mutations and I presume Pfizer is too, along with other vaccine manufacturers. We also need to know if the new mutation is still detected by our standard molecular and antigen tests. We should have this information fairly soon, maybe even this month.
I did find a few useful web sites for anyone to learn more. The European Centre for Disease Prevention and Control has a nice Executive Summary of the situation.
Bottom line: no reason for great concern, but we should learn more about this in the next several days.