Vaccine coverage in PLWH: disparities and potential impact of vaccine hesitancy

Dear Editor,

We read with great interest the article by Tsachouridou et al. entitled “Factors associated with poor adherence to vaccination against hepatitis viruses, Streptococcus pneumoniae and seasonal influenza in HIV-infected adults”.¹ The authors aimed to identify risk factors for non-adherence to routine vaccination in HIV-infected patients. They evaluated vaccine coverage in 1210 HIV-infected patients against hepatitis A virus (HAV), hepatitis B virus (HBV), seasonal influenza and invasive pneumococcal diseases (IPD). We performed a similar study in our cohort of HIV-infected patients; our aim was to evaluate vaccine coverage for routine vaccinations, and to identify factors associated with poor adherence, particularly patients’ beliefs and attitudes toward vaccines. We included 561 HIV-infected patients, and 468 (83,4%) of them answered a self-questionnaire assessing their beliefs and attitudes towards vaccines. We observed a significantly lower vaccine coverage than Tsachouridou et al. against HAV, HBV, and IPD.¹ In our cohort, vaccine coverage against IPD was 20 % versus 79 % in the Greek cohort. Vaccine coverage for HAV and HBV were respectively 23.7% and 63.5% in our cohort, contrasting with the 73.6% and 73.6% observed in the Greek study. However, vaccine coverage against seasonal influenza was quite similar, 40.1 % in our cohort and 39 % in the Greek cohort.¹ The observed difference in vaccine coverage in people living with HIV between Greece and France are not explained by different guidelines or by costs, as in both countries, all four vaccines are recommended in PLWH and without additional costs for patients.^1,2 To explain the observed differences, we formulate several hypotheses. First, we can suggest that mistrust in vaccines may contribute to the observed differences. France is the leading country for vaccine hesitancy, and more than 40 % of the French people considered the safety of vaccines as doubtful.³ In our cohort, 10.3 % of the respondents to the self-questionnaire declared to be firmly against vaccines.

Secondly, in Greece, vaccines are provided free of charge by the hospital to PLWH, in France, vaccines are also provided free of charge for PLWH, but not directly by the hospital, and patients should take vaccines in a pharmacy and vaccines are administered by a physician. This discrepancy between the two systems suggests that active offer of vaccinations in HIV clinics may help to improve vaccine coverage. Active offer of vaccines during the hospital stay in splenectomized patients and in hospitalized adults^4,5 was associated with an increase in adherence to vaccination.

Tsachouridou et al. observed a negative impact of the 2010 financial crisis on vaccine coverage against HAV, HBV, and pneumococcal disease.¹ They did not observe any difference for the vaccine coverage against seasonal influenza. The absence of impact is probably due to the fact that vaccine coverage against seasonal influenza is very low. The vaccine coverage in Greek PLWH was as low as the vaccine coverage observed in our study. Vaccine coverage against seasonal influenza was also very low in a US Cohort of PLWH around 42 %⁶ and in another French cohort of PLWH around 30.9 %.⁷ There is a real issue with vaccination against seasonal influenza in PLWH. We suggest that vaccine hesitancy is particularly high for vaccination against seasonal influenza in PLWH. Among the 143 unvaccinated against seasonal influenza responders to our questionnaire, 29 (20.3%) declared to be firmly opposed to this vaccine, 52 (36.4 %) considered vaccine against seasonal influenza as futile, and 19 (13.3 %) were feared about side effects. In univariate analysis, older age and suffering from another comorbidity was associated with a better adherence to seasonal influenza vaccine. In multivariate analysis, only older age remained associated with adherence. Tsachouridou et al. also observed an association between older age and adherence to seasonal influenza vaccine. In contrast, in their cohort, lower level of education and lack of insurance were associated with non adherence.¹ In France, PLWH receive each year a voucher from the National Health Insurance for a free vaccine against seasonal influenza. In our cohort, vaccine coverage against seasonal influenza increased to 68.4 % in patients receiving a piece of information by HIV specialists or general practitioners, and was significantly higher than in patients who only received a voucher. Transient increase in HIV viral load observed after seasonal influenza vaccination was not considered by patients as an issue, only two patients were afraid to observe an increase in HIV viral load.⁸ Curiously, 13.3 % patients were feared about side effects of seasonal influenza vaccine. In contrast, only 4 % had fears about side effects of vaccine against pneumococcal disease, whereas more than 50 % of the patients did not get any information about the vaccine against pneumococcal disease. These different observations suggest that the vaccine against seasonal influenza is not considered like another one by the PLWH.

In conclusion, efforts are needed to increase vaccine coverage in PLWH, particularly against seasonal influenza and pneumococcal disease. Vaccine hesitancy is probably an issue in patients living with a chronic infection like HIV. Delivering a targeted information by HIV-specialists concerning vaccinations is probably a good way to increase vaccine coverage in PLWH. A special effort should be made to better advocate seasonal influenza vaccine in PLWH.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the authors.