In this systematic scoping review, fifteen studies were assessed, which that the obtained results were summarized in two areas. Here, we will discuss the findings.
1) The effect of vaccination
Caldera et al. revealed that all control group and 97% of patients with IBD developed antibodies. Antibody concentrations were lower in patients with IBD. Those who received Moderna had higher antibody concentrations compared with those who received the Pfizer vaccine series. Also, patients on immunemodifying therapy had lower antibody concentrations compared with those who were on no treatment, aminosalicylates, or vedolizumab (14).
Also, Cerna et al. stated that the post vaccine seropositivity rate among IBD patients and controls was 97.8% vs 100%. Median anti-Covid-19 IgG levels were lower among IBD recipients of AstraZeneca compared with 2 other vaccines and control AstraZeneca recipients. These were no correlation between serum trough levels and anti-Covid-19 IgG concentrations for any of the biological drugs used. The TNF-α inhibitors with concomitant immunosuppressive treatmen,t but no other treatment modalities were associated with a lower postvaccination antibody response. The laboratory activity of IBD evaluated by C-reactive protein and fecal calprotectin levels. However, there were no significant differences before the vaccination and 8 weeks after its completion (28).
Classen et al. reported that all patients with IBD (100%) developed an immune response after full vaccination. Also, there was no significant difference in antibody levels between the 3 different vaccines received upon first vaccination. The kind of IBD disease and medication had no significant effect on the level of antibody titers. Also, they found that compared to the healthy group, reduced antibody response was detected. There was no vaccination failure in the IBD group after 2 doses vaccinations. In patients with IBD, antibody titers were positively associated with days between last vaccination and blood sample taken, whereas in the control group, antibody titers negatively correlated with the days after dose 1. Moreover, the days between two doses of vaccination had no impact on antibody response in both groups (18).
Similarly, Levin et al. showed a 95% overall response rate after Covid-19 vaccination. Also, none of the patients with positive results for spike domain antibodies had elevations of nucleocapsid antibodies, suggesting a true vaccine response rather than prior undiagnosed infection. In patients with elevated spike domain antibodies (a true vaccine response rather than prior undiagnosed infection), 89% had the highest measurable levels, at >250.00 U/mL, with assay reference ranges of 0.79 U/mL indicating negative and 0.80 U/mL (positive results) (29).
Lev-Tzion et al. indicated that overall 0.3% developed Covid-19 after vaccination. Infection rates were slightly higher in the unvaccinated IBD patients compare to non IBD patients. Also, patients on tumor necrosis factor (TNF) inhibitors and/or corticosteroids did not have a higher incidence of infection. No difference in disease outcome was observed during the first 40 days after the second vaccination, however time to flare was shorter in vaccinated compared with unvaccinated IBD patients (10).
In another study, Edelman-Klapper et al. found that Covid-19 anti-S IgG antibodies in all control group were seropositive, whereas about 7% of patients with IBD, regardless of treatment, remained seronegative after dose 1, and it was positive in all patients after dose 2. It means that neither IBD itself nor anti-TNFa treatment eliminate the ability to mount serologic response to vaccination. However, anti-TNFa treatment was associated with significantly lower antibody levels compared with non-anti-TNFa treated patients, and control group. Also, neutralizing and inhibitory functions were both lower in anti-TNFa treated compared with non-anti-TNFa treated patients, and control group. Moreover, Anti-TNFa drug levels and vaccine responses did not affect anti-spike levels. But, IBD activity was unaffected by vaccination. The results of multivariate linear regression model showed that only anti-TNFa treatment and older age maintained a significant distinct association with lower IgG anti-S response (19).
Kappelman et al. found antibody response was decreased in IBD patients receiving systemic corticosteroids. In these patients, the proportion of detectible antibodies was 85% versus 95% among non-steroid users. However, antibody response was generally similar across age group, vaccine type, and use of other classes of IBD medications (22).
Moreover, Kennedy et al. showed that the concentration of anti-Covid-19 antibody following vaccination were lower in patients treated with infliximab than vedolizumab. Multivariable models indicated that antibody concentrations were lower in patients treated with infliximab compared with vedolizumab. Age ≥60 years, immunomodulator use, Crohn’s disease and smoking were related with lower, while non-white ethnicity was related with higher Covid-19 antibody concentrations. Moreover, seroconversion rates after a single dose of either vaccine were higher in patients with prior Covid-19 infection and after two doses of Pfizer vaccine (23).
In a study by Pozdnyakova et al., it was revealed that two weeks after vaccination, positive antibody levels were detected in more than 90% of IBD patients. Tthe multivariable analysis showed that at week 2, only vaccine type was associated with antibody levels, with both Moderna and Pfizer having significantly higher levels than Jahnson & Jahnson. Also, at week 8, vaccine type remained independently associated with antibody levels. On the other hand, lower titers were independently associated with both a longer duration between completion of vaccine regimen and blood sampling and IMT receiving. They concluded that positive levels of IgG(S) were achieved in virtually all IBD vaccine recipients regardless of vaccine type and IMT use (24).
Furthermore, total IgG antibodies increased 21.13 times after dose 1 and 90 times after dose 2 in Rodriguez-Martino et al.’s study. VTN% increased 11.92 times after dose 1 and 53.79 times after dose 2. Total IgG antibodies and VTN% were lower in IBD patients after dose 2. In their study, IgG antibodies increased after dose 2, but remained lower than control group. However, VTN% were similar to controls after dose 2. CD4 and CD8 mean levels had an upward trend after vaccination (25).
In Shehab et al.’s study, in patients being treated with infliximab and adalimumab, the proportion of patients who achieved positive anti-Covid-19 IgG antibody levels after receiving two doses of the vaccine were 74.5% and 81.2%. Also, it was found that in patients receiving ustekinumab and vedolizumab, the proportion of patients who achieved positive anti-Covid-19 IgG antibody levels after receiving two doses of the vaccine were 100% and 92.8%. In patients receiving infliximab and adalimumab, the proportion of patients who had positive anti-Covid-19 neutralizing antibody levels after two-dose vaccination were 67.7% and 87.5%. The proportion of patients who had positive anti-Covid-19 neutralizing antibody levels were 92.3% and 92.8% in patients receiving ustekinumab and vedolizumab (26).
It was reported in Wong et al.’s study that all IBD patients with 2 doses of vaccination, had positive anti-RBD tests, of whom 84.6% achieved index levels. Also, it was found that anti-TNF were related to lower anti-RBD total immunoglobulin. Moreover, Vedolizumab was associated with lower anti-RBD total immunoglobulin, anti-RBD IgG, and anti-S IgG than in control group. The results of multiple linear regression analyses showed no association between timing of infusion and antibody response (27).
2) Side effects
Totally, seven studies mentioned the side effects of Covid-19 vaccinations in patients with IBD (17-21, 27, 28).
In the study by Edelman-Klapper et al., it was reported that immediate and short-term side effects s were detected using phone call and accepted questionnaires, respectively. However, no severe adverse events were reported. Side effects were more after dose 2 compared with dose 1. The most common side effects were local pain (<70%) and headache (about 30%). Infection rate (about 2%) and side effects were similar in all groups (19).
In another study by Botwin et al., the most common severe symptom after dose 1 was fatigue/malaise (3%); other severe symptoms were reported by 2% or fewer subjects. The most common severe symptoms after dose 2 included fatigue/malaise (10%), fever/chills (8%), and headache (8%). Most symptoms resolved in less than 2 days except for injection site reactions, which mostly resolved within 7 day. Also, it was reported that 39% of patients suffered from side effects after dose 1, and 62% after dose 2. The frequency of side effects was similar to the general population. Also, they found that the frequency of side effects was less common in individuals receiving biologic therapy, and it more in those with prior Covid-19. However, they found that side effects were more common among younger patients, and the massive majority of adverse effects were non-severe. Severe side effects (defined as preventing daily activity) were observed in few patients and 3 patients were hospitalized after dose 1 (17).
Also, Garrido et al. stated that the frequency of side effects was 56.8% after dose 1 and 74.1% after dose 2. Also, it be lower than general population during the first week after vaccination. No serious side effects were reported and all side effects were mild and transitory, and lasted only a few days without any necessity of patients' hospitalization. The percentage of side effects was higher among patients younger than 50 years. However, side effects were reported to be similar in patients with different sex, vaccine type, biological drug or disease type. They finally concluded a high acceptance rate and a good safety profile of Covid-19 vaccination in IBD patients treated with biologics, and diverse effects were common but overall mild and transitory (20).
It was found in Classen et al.’s study that in the IBD group, 58.3% patients had significantly more side effects after dose 1 compared to the control group. But, after dose 2, the side effects were higher in the control group, significantly. The observed side effects after dose 1 were muscle pain, pain at the injection site, and fatigue, which were not significantly higher in IBD patients than in the control group. Similar complaints occurred after dose 2 (with pain at the injection site, fatigue, muscle pain, and fever being the most frequent complaints)(18).
Hadi et al. reported that special adverse events of interest developed in 2.03% patients with IBD, and in 0.81% patients without IBD. There was no significant difference in adverse events of special interest and a new diagnosis of Covid-19 in two groups. Also, it was similar in the 30-day hospitalization after the Covid-19 vaccination, after matching. No difference was found in steroid prescription at the 1 month follow-up in vaccinated and unvaccinated patients with IBD in unmatched and matched analysis. No difference in 30-day adverse events of special interest after the vaccination between patients with IBD with and without biologic or immunomodulator use, and also between patients with CD and UC were found. No difference in steroid use after vaccination was found between patients with and without biologic or immunomodulator use, or both, and between patients with CD and UC (21).
Finally, the results of Wong et al.’s study showed that Covid-19 vaccination’s side effect was not different in vaccinated IBD patients compared vaccinated non-IBD healthcare workers (27).
It is worth to mention that IBD exacerbation was reported in the Garrido et al. and Lev-Tzion et al.’s studies (10, 20). IBD exacerbation was defined as treatment escalation, commencement of corticosteroids or enema, or hospitalization. Lev-Tzion et al. found that 44% of vaccinated and 34% of unvaccinated patients experienced an exacerbation or treatment escalation, and this difference was statistically significant. However, the overall risk of exacerbation was 29% in vaccinated patients and 26% in unvaccinated patients, which was statistically similar (10).
The main characteristics of the current systematic scoping review on IBD patients and Covid-19 vaccination was the simultaneous comparison of the complications and benefits of various vaccination. The main limitation of this study was that lack of any clinical trial study, specially randomized controlled trial.
It was concluded that regardless of the vaccine type, IBD patients that receiving immunosuppressive drugs need more careful monitoring of the effects of the vaccine, including screening for antibodies against the Covid-19 virus, as well as more booster doses. On the other hand, the concern that exists among patients with IBD about the side effects of the vaccine was investigated in various studies and it was revealed that the vaccine does not lead to worsening of the disease and the side effects are almost the same like other healthy people. According to existing studies, vaccination has not led to flare of IBD, too.
As a final conclusion, patients with IBD can be advised that vaccination may have limited minor side effects, but it can protect them from the serious complications of Covid-19 disease and its resulting mortality with a high success rate.