Decoding Use of Vaccination in Immunocompromised Adults - Dr Jyotish R Nair

Vaccination stands as one of the most pivotal developments in the field of medicine, profoundly enhancing the quality of life for the human race. It has effectively tackled numerous diseases that once wreaked havoc, either eradicating them entirely or significantly limiting their spread.

However, the success stories of vaccination predominantly feature immunocompetent individuals—those with normal immune systems capable of generating antibodies in response to viral or bacterial threats. Even within this population, vaccine efficacy can vary from person to person. Nevertheless, due to herd immunity and other natural mechanisms, most vaccination programs achieve excellent results.

The immunocompromised adult presents a distinct challenge. Their immune system may lack the capability to eradicate invading pathogens or generate a sufficient antibody response. This compromised state can arise from congenital conditions, acquired disorders or diseases, or immunosuppressive medications. Deficiencies may exist in cellular, humoral, or both components essential for immunity.

Consequently, immunity levels in vaccinated individuals may decrease, necessitating additional vaccine doses or higher potency to attain adequate protective antibodies. This population faces an elevated risk of vaccine-preventable diseases or complications and heightened susceptibility to adverse events, particularly with live vaccines. Physicians encounter difficulty in assessing the extent of immune deficiency and determining the necessity for further immunization.

Live vaccines that are commonly used include the BCG (bacille Calmette–Guérin) vaccine, oral cholera vaccine, some Japanese encephalitis virus vaccines, MMR (measles-mumps-rubella) vaccine, rotavirus vaccine, oral typhoid vaccine, varicella vaccine, yellow fever vaccine, zoster vaccine (Zostavax). The live strains can produce unchecked infection and are hence generally contraindicated in the severely immunocompromised.

People who are severely immunocompromised include those who have active leukaemia or lymphoma, or other generalized malignancy, have received recent chemotherapy or radiotherapy, have HIV (certain people only), had a solid organ transplant or hematopoietic stem cell transplant less than 2 years ago, or are still immunocompromised or taking immunosuppressive drugs, or have graft-versus-host disease, are taking highly immunosuppressive therapy, including bDMARDs or tsDMARDs (biological or targeted synthetic disease-modifying anti-rheumatic drugs), or high-dose corticosteroids, have certain autoimmune diseases, particularly if they are on highly immunosuppressive therapy, have aplastic anemia, or have congenital immunodeficiency.

People who may be only mildly immunocompromised include those who are receiving selected csDMARDs (conventional synthetic DMARDs) in low doses, either on their own or in combination with low-dose corticosteroids (<20 mg per day of prednisone-equivalent dose). These people can receive some live vaccines (for example, zoster vaccine). Examples of low-dose csDMARDs are methotrexate ≤0.4 mg per kg per week, azathioprine ≤3.0 mg per kg per day, mercaptopurine ≤1.5 mg per kg per day.

People receiving corticosteroids have varying degree of immunosuppression based on the dose and duration of the molecule used. Generally, a dose of 20mg prednisolone equivalent per day for more than 14 days is considered as high dose. Live attenuated vaccines (such as MMR, MMRV [measles-mumps-rubella-varicella], zoster [Zostavax], varicella and yellow fever) may be unsafe in people receiving corticosteroid therapy.

People receiving an immunosuppressant should be reassessed after an appropriate interval after completing treatment to consider vaccination with live vaccines. Inhaled steroids are considered safe and are not, by themselves alone, a contraindication for live vaccines.

If an immunosuppressed individual is inadvertently vaccinated with a live vaccine, their immune status should be reassessed and if required should be managed with immunoglobulin, or antiviral or antibacterial therapy, depending on the vaccine and clinical context.

People who are immunocompromised are recommended to receive inactivated vaccines like influenza vaccine, pneumococcal vaccine, meningococcal vaccine, HPV vaccine, hepatitis B vaccine, recombinant zoster vaccine (Shingrix) and COVID-19 vaccine.

Influenza vaccination is recommended annually due to the new strains appearing each year. If a major shift in the circulating influenza virus occurs, such as during an influenza pandemic, the immunocompromised might benefit from receiving 2 doses of inactivated influenza vaccine, at least 4 weeks apart, regardless of their previous influenza vaccination history.

Extra doses of pneumococcal and meningococcal vaccines are required, whereas higher-strength doses, double doses or additional doses of hepatitis B vaccines are recommended in the immunocompromised. The risk of severe illness from SARS-CoV-2 is higher in people with immunocompromised, and all such people are recommended to receive COVID-19 vaccine.

Household contacts and other close contacts of people who are immunocompromised should be fully vaccinated according to current recommendations. Their vaccination history should be reviewed, and they should receive any necessary catch-up doses.

There is no risk of transmission of the MMR vaccine viruses, and an almost negligible risk of transmission of varicella-zoster vaccine virus (from varicella or zoster vaccine). However, there is a small risk of transmission of the rotavirus vaccine virus. This can be minimised by handwashing and careful disposal of soiled nappies.

People with severe neutropenia (absolute neutrophil count <0.5 × 10⁹ per L) should not receive any vaccines, to avoid an acute febrile episode.

Where possible, children and adults having a solid organ transplant should receive all routine scheduled or catch-up vaccines well before transplantation. It is important to administer all necessary live vaccines at least 1 month before solid organ transplantation, where possible.

Protective immunity to vaccine-preventable diseases is partially or completely lost after an allogeneic or autologous haematopoietic stem cell transplant (HSCT). Do not give live vaccines to HSCT recipients until 24 months after the transplant, and provided that the person has no ongoing immunosuppression. HSCT recipients usually have a poor immune response to inactivated vaccines during the first 6 months after HSCT, and hence should be deferred.

People with HIV should have vaccination schedules based on their age, CD4⁺ count (which indicates how immunocompromised they are), risk of infection and concurrent medical conditions or medications (which may be immunocompromised).

Thus, we see that vaccination of the adult immunosuppressed depends upon several factors, and they should undergo vaccination after carefully weighing the pros and cons. Carefully selected and administered vaccines can be protective and should be recommended.