Safety and immunogenicity of a primary yellow fever vaccination under low-dose methotrexate therapy-a prospective multi-centre pilot study1

Impact of methotrexate treatment on vaccines immunogenicity in adult rheumatological patients - Lessons learned from the COVID-19 pandemic

Despite the development of new biological and synthetic targeted therapies, methotrexate remains one of the most commonly used immunomodulatory drugs in rheumatology. However, its effect on the immunogenicity of vaccines has been studied only to a limited extent until recently, resulting in the lack of clear guidelines on the use of methotrexate during vaccination. Significant progress was made during the COVID-19 pandemic due to the dynamic development of research on vaccines, including patients with autoimmune inflammatory rheumatic diseases. In the following literature review, we present a summary of what we know so far on the impact of methotrexate on post-vaccination response in adult rheumatology patients, taking into account the lessons learned from the COVID-19 pandemic. Studies on the effect of methotrexate on the immunogenicity of influenza, pneumococcal, herpes zoster, tetanus/diphtheria/pertussis, hepatitis A, yellow fever, and COVID-19 vaccines are described in detail, including the effect of methotrexate on the humoral and cellular response of individual vaccines. The available evidence for recommendations for withholding methotrexate in the post-vaccination period is presented. Lastly, an overview of potential immunological mechanisms through which MTX modulates the immunogenicity of vaccinations is also provided.

Yellow fever vaccine safety in immunocompromised individuals: a systematic review and meta-analysis

BACKGROUND

Yellow fever is an arbovirus with variable severity, including severe forms with high mortality. The vaccination is the most effective measure to protect against the disease. Nonserious and serious adverse events have been described in immunocompromised individuals, but previous studies have failed to demonstrate this association. This systematic review assessed the risk of adverse events after yellow fever vaccination in immunocompromised individuals compared to its use in non-immunocompromised individuals.

METHODS

A search was conducted in the MEDLINE, LILACS, EMBASE, SCOPUS, DARE, Toxiline, Web of Science and grey literature databases for publications until February 2021. Randomized and quasi-randomized clinical trials and observational studies that included immunocompromised participants (individuals with HIV infection, organ transplants, with cancer, who used immunosuppressive drugs for rheumatologic diseases and those on immunosuppressive therapy for other diseases) were selected. The methodological quality of observational or non-randomized studies was assessed by the ROBINS-I tool. Two meta-analyses were performed, proportion and risk factor analyses, to identify the summary measure of relative risk (RR) in the studies that had variables suitable for combination.

RESULTS

Twenty-five studies were included, most with risk of bias classified as critical. Thirteen studies had enough data to carry out the proposed meta-analyses. Seven studies without a comparator group had their results aggregated in the proportion meta-analysis, identifying an 8.5% (95% CI 0.07-21.8) risk of immunocompromised individuals presenting adverse events after vaccination. Six cohort studies were combined, with an RR of 1.00 (95% CI 0.78-1.29). Subgroup analysis was performed according to the aetiology of immunosuppression and was also unable to identify an increased risk of adverse events following vaccination.

CONCLUSIONS

It is not possible to affirm that immunocompromised individuals, regardless of aetiology, have a higher risk of adverse events after receiving the yellow fever vaccine.

Impact of disease-modifying antirheumatic drugs on vaccine immunogenicity in patients with inflammatory rheumatic and musculoskeletal diseases

Patients with rheumatic diseases are at increased risk of infectious complications; vaccinations are a critical component of their care. Disease-modifying antirheumatic drugs may reduce the immunogenicity of common vaccines. We will review here available data regarding the effect of these medications on influenza, pneumococcal, herpes zoster, SARS-CoV-2, hepatitis B, human papilloma virus and yellow fever vaccines. Rituximab has the most substantial impact on vaccine immunogenicity, which is most profound when vaccinations are given at shorter intervals after rituximab dosing. Methotrexate has less substantial effect but appears to adversely impact most vaccine immunogenicity. Abatacept likely decrease vaccine immunogenicity, although these studies are limited by the lack of adequate control groups. Janus kinase and tumour necrosis factor inhibitors decrease absolute antibody titres for many vaccines, but do not seem to significantly impact the proportions of patients achieving seroprotection. Other biologics (interleukin-6R (IL-6R), IL-12/IL-23 and IL-17 inhibitors) have little observed impact on vaccine immunogenicity. Data regarding the effect of these medications on the SARS-CoV-2 vaccine immunogenicity are just now emerging, and early glimpses appear similar to our experience with other vaccines. In this review, we summarise the most recent data regarding vaccine response and efficacy in this setting, particularly in light of current vaccination recommendations for immunocompromised patients.

A clinician's perspective on yellow fever vaccine-associated neurotropic disease

Yellow fever (YF) causes high fever, liver dysfunction, renal failure, hypercoagulopathy and platelet dysfunction and can lead to shock and death with a case-fatality ratio of 20-50%. YF vaccination results in long-lasting protective immunity. Serious adverse events (SAEs), such as YF vaccine-associated neurotropic disease (YEL-AND) are rare. We present a case of a 56-year-old Caucasian man with fever, headache, cognitive problems at the emergency department. He received a primary YF vaccination 4 weeks prior to symptom onset. Cerebrospinal fluid tested positive (POS) for YF virus by reverse transcriptase polymerase chain reaction and confirmed diagnosis of YEL-AND. The patient recovered with symptomatic treatment. We reviewed published clinical reports on YEL-AND indexed for MEDLINE. We identified and analyzed 53 case reports. Forty-five patients were male and eight were female. Twenty-nine cases met criteria for definite YEL-AND and twenty-four for suspected YEL-AND according to YF Vaccine Safety Working Group. We applied the Brighton Collaboration diagnostic criteria to assess the diagnostic accuracy of the clinical diagnoses and found meningoencephalitis in 38 reported YEL-AND cases, Guillain Barré Syndrome (GBS) in seven, Acute Disseminated Encephalomyelitis (ADEM) in six and myelitis in five. Thirty-five patients recovered or improved; however, not all cases had a complete follow-up. The prognosis of YEL-AND presenting with GBS, ADEM or myelitis was poor. Fourteen patients received therapy (corticosteroids, intravenous immunoglobulins and/or plasmapheresis). In conclusion, YF vaccine-associated neurotropic disease is a very rare but SAE after YF vaccination. We described a case of YEL-AND and propose a standardized clinical workup of this condition based on a review of the literature. Centralized registration of complications of YF vaccination is encouraged.