COVID vaccines and MS drugs: no delays needed for most

During this period of COVID vaccination, concerns were raised about whether the disease-modifying therapies (DMTs) that control MS could impair a person’s response to a vaccine. DMTs work by modifying the immune response in various ways. This can work at cross-purposes from vaccines, which are intended to stimulate this same immune response to enable the body to fight infection.

Fortunately, most people with MS on a DMT are taking one of the “first-line” therapies, either an oral drug (Aubagio or Tecfidera) or an injectable therapy (Copaxone, Avonex, Rebif, Plegridy, Betaseron/Extavia). These medications generally do not reduce the number of immune cells so the body’s ability to mount an immune response to a vaccine is not greatly affected. In fact, a recent study suggested that Aubagio may have antiviral effects (Hahn and colleagues. Viruses 2020;12:1394). Similarly, one study found that Tecfidera could inhibit the growth of the CoV-2 virus that causes COVID (Olagnier and colleagues. Nat Commun 2020;11:4938).

Few studies have specifically looked at the response to a COVID vaccine while on an oral or injectable DMT. However, some information can be gleaned from studies with other types of vaccines. For example, the interferons (Avonex, Rebif, Plegridy, Betaseron/Extavia) were shown to have little impact on the response to the H1N1 (swine flu) vaccine, although the response was less robust for those taking Copaxone in that study (Olberg and colleagues. Mult Scler 2014;20:1074-1080). People taking Aubagio generally mounted an adequate immune response to seasonal flu shots (Bar-Or and colleagues. Neurology 2013;81:552-558). In addition, people on Tecfidera have been shown to mount an effective immune response to various vaccines, including tetanus, pneumonia and meningitis (von Hehn and colleagues. Neurol Neuroimmunol Neuroinflamm 2017;5:e409).

All of these treatments are taken at short intervals, so it was reassuring that people responded even though they had active drug in their systems at the time of vaccination.

These vaccine studies explain why expert groups, such as the MS International Federation (MSIF), have stated that people taking Aubagio, Tecfidera or an injectable should keep to their usual regimen before and after COVID vaccination ( If you are ready to start treatment, you can do so right away if you and your doctor have decided on one of these DMTs. If you are already taking one of these treatments, there is no need to interrupt your therapy to accommodate a vaccination appointment. You can continue with your usual regimen before, during and after your vaccine appointment.

The situation is a little different for people taking a more potent MS treatment since most reduce the number of circulating immune cells. Thus far, the greatest concerns have been with Ocrevus, which reduces the number of immune cells (called B cells) available to fight infection. Numerous studies have indicated that the response to COVID vaccine is blunted with Ocrevus (Achiron and colleagues. Mult Scler 2021;27:864-870. Gallo and colleagues. Neurol Sci 2021, epublished June 15, 2021. Bigaut and colleagues. Rev Neurol (Paris) 2021, epublished June 16, 2021). This impaired response was consistent with what has been seen in other vaccine studies with Ocrevus (Bar-Or and colleagues. Neurology 2020;95:e1999-e2008). While there are many questions still to be answered, it could mean that people on Ocrevus who have a less robust response may need a third shot of vaccine to further boost their immunity and protect them against COVID.

The MSIF also states that people taking Gilenya, Mayzent or Zeposia may also have a reduced response to COVID vaccines. Vaccine studies with Gilenya have reported some impairment in the vaccine response although the evidence is very mixed (Boulton and colleagues. J Clin Pharmacol 2012;52:1879-1890). The one published vaccine study with Mayzent reported little effect on vaccine effectiveness (Ufer and colleagues. Neurol Neuroimmunol Neuroinflamm 2017;4:e398). No vaccine studies for Zeposia have been published.

Mavenclad and Lemtrada are dosed infrequently so their effect on immune cells is intermittent. Mavenclad does not have a profound effect on immune cells, so the MSIF recommends that people get vaccinated at any point in their course of treatment. With Lemtrada, it is advisable to wait at least 6 months after the last dose before getting vaccinated.

Tysabri does not have profound effects on immune cell numbers and vaccine studies generally show that treatment does not have a significant effect on a person’s response to vaccination (Kaufman and colleagues. J Neurol Sci 2014;341:22-27). So there is no need to change the usual dosing schedule of one infusion every four weeks, although some doctors may opt for treatments every five or six weeks.

It is important to note that when determining vaccine response, the measure that is typically used is the level of antibodies detected in response to the vaccine. Antibodies are produced from B cells, so reducing the number of B cells (with treatments like Ocrevus or Kesimpta) would be expected to reduce the number of antibodies in the blood stream. However, antibodies are only part of the immune response to vaccines, and these other components may respond sufficiently to ward off infection. More studies will be needed to provide a more accurate picture of how well people with MS respond to COVID vaccination. In the meantime, the MSIF recommends that people go ahead with getting their COVID shot – but to continue to take precautions against COVID in case you are still vulnerable to infection after vaccination.

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