In December 2019, cases of pulmonary infection secondary to a novel coronavirus, known as severe acute respiratory syndrome coronavirus 2, were first identified in the city of Wuhan, China.
The clinical disease caused by the virus, COVID-19, has resulted in a worldwide pandemic that has portended significant morbidity and mortality throughout the United States. Three highly efficacious COVID-19 vaccines have received emergency use authorization (EUA) by the Food and Drug Administration to help prevent COVID-19, all of which are effective at preventing severe COVID-19.1-3 The Pfizer vaccine was given full FDA approval on Aug. 23, 2021.4
Patients with inflammatory bowel disease (IBD) are commonly treated with immune-modifying therapies that may increase their risk for serious and opportunistic infections. As such, there was concern at the beginning of the pandemic that patients with IBD may be at increased risk of contracting COVID-19 and/or developing severe disease (that is, ICU-level care, mechanical ventilation, and/or death). There is evidence that the incidence of COVID-19 in the IBD population is similar to that of the general population.5-7 Furthermore, most patients with IBD are not at increased risk of severe disease, including those on biologic therapies. Several studies demonstrated that those on corticosteroids are at increased risk of severe COVID-19, while those on other immune-modifying therapies such as tumor necrosis factor inhibitors (anti-TNFs) are not at increased risk.5,7-10 Patients with IBD with other well-known risk factors for severe disease include comorbidities such as diabetes and obesity.
It is known that patients with IBD on certain immune-modifying therapies such as anti-TNFs, especially those on combination therapy, may have a blunted immune response to certain vaccines.11 Neither patients with IBD nor patients on immunosuppressive therapy were included in phase 3 clinical trials for COVID-19 vaccine development, contributing to uncertainty regarding the safety and efficacy in our patient population. The risk of adverse events following COVID-19 vaccination in the IBD population has been found to be similar to that of the general population.12 It has also been reported that those who have had reactions to injectable therapies in the past may safely be vaccinated against COVID-19.13,14 With regard to vaccine efficacy, initial studies, including ICARUS, PREVENT-COVID, and CORALE-IBD, have demonstrated that patients with IBD do indeed mount a humoral immune response to the vaccine, including those on immune-modifying therapies.15-17 Nonhumoral aspects of immunity, such as cell-mediated immunity, have not yet been thoroughly evaluated. In addition, the risk of breakthrough COVID-19 infection after vaccination is low in patients with IBD, including those on immune-modifying therapy.14-18 While initial studies are reassuring that the vast majority of patients with IBD are able to mount a vaccine response, future studies are needed to determine the effects of immune-modifying therapy on sustained antibody concentrations and other correlates of immunity.
For those who received the Pfizer or Moderna vaccines, on Aug. 12, 2021, the FDA amended their EUA to allow for an additional dose in the initial vaccination series for certain immunocompromised individuals, specifically solid organ transplant recipients or those with conditions that make them equally immunocompromised.19 Based on evidence suggesting that certain solid organ transplant recipients do not mount an immune response after completing a two-dose series, the Advisory Committee on Immunization Practices, which advises the Centers for Disease Control and Prevention on how to use vaccines, recommended that moderate to severely immunocompromised individuals should complete a three-dose series, with the third dose being given at least 28 days after the second dose.20 This recommendation included those on high-dose corticosteroids defined as oral prednisone at least 20 mg/day, anti-TNFs and biosimilars, and antimetabolites such as azathioprine, mercaptopurine, and methotrexate.
It is worth noting that the role of the ACIP here was to consider the available evidence supporting the use of an additional dose and then make recommendations on which conditions may qualify; the ACIP was not able to provide recommendations for every disease state. At the time of writing this article, no recommendations have been made with regards to an additional dose of the Janssen vaccine. Likewise, in response to the ACIP recommendations, the Crohn’s & Colitis Foundation recommended an additional dose for patients with IBD on immune-modifying therapies.21,22
Less than one week after the EUA amendment for an additional dose, the Department of Health & Human Services announced that booster shots would likely become available to the general population as early as the week of Sept. 20, 2021 and starting 8 months after an individual’s second dose.23 Here, it is worth noting that an additional dose is distinct from a booster. An additional dose (or third dose here) refers to the initial vaccination series and is given when the standard schedule is thought to be insufficient in a certain patient population. In contrast, a booster dose is administered when the initial and sufficient immunity gained from a primary vaccination series has likely dissipated. The HHS acknowledged that boosters would likely be needed for those who received the Janssen vaccine but noted that further data and recommendations would be forthcoming.
To summarize, COVID-19 vaccines are safe and effective in the IBD population, and patients should be vaccinated at the earliest opportunity regardless of concurrent therapies. For those that received the Pfizer or Moderna vaccine, the ACIP recommended an additional dose in the initial vaccination series to be given at least 28 days after the second dose for those that are immunosuppressed. This recommendation was largely based off of transplant data. Reassuringly, the available data demonstrates a humoral immune response to a two-dose vaccination series in patients with IBD, including those on immune-modifying therapies. The Crohn’s & Colitis Foundation recommends that patients with IBD on immune-modifying therapy receive an additional dose (i.e., a three-dose series), which should be from the same manufacturer as the first two doses. In addition, at press time, HHS indicated that there will be a movement toward a booster dose for the general population in late September, which would also apply to patients with IBD. The ACIP has yet to comment on this change at the time of preparing this article, but the announcement indicated that a booster could be given “8 months after an individual’s second dose.” It is unclear how those who may receive a three-dose vaccination series will factor in, but it is possible that they would be eligible for a booster 8 months after their most recent dose. Gastroenterologists should also be aware that there is no role for serologic testing in the clinical setting because it has not been validated for such purposes and is primarily used in the research setting. Finally, it is paramount to emphasize that patients with IBD have historically had lower vaccination rates than the general population,24 and we must take an active role in ensuring that our patients are immunized by addressing their concerns, communicating the risks of COVID-19 and the benefits of vaccination, providing information on how to get vaccinated, and strongly recommending vaccination.