Pandemic influenza: implications for programs controlling for HIV infection, tuberculosis, and chronic viral hepatitis

Uptake, barriers and correlates of influenza vaccination among people who inject drugs in Australia

BACKGROUND

Comorbid chronic health conditions place people who inject drugs (PWID) at risk of severe health outcomes after influenza infection. However, little is known about the uptake, barriers and correlates of influenza vaccination among PWID.

METHODS

During structured surveys, 872 PWID reported whether they had received an influenza vaccination during the last year (disaggregated as pre- or post-March 2020 to ascertain current season vaccine uptake), and if not, the barriers to vaccination. Logistic regression was used to examine demographic, drug use, health and service engagement correlates of vaccine uptake.

RESULTS

Thirty-nine percent of participants reported past-year influenza vaccination, with one-quarter (24 %) vaccinated in the current season. The main barriers to vaccination were motivation-based, with few citing issues relating to affordability, supply or perceived stigma. Opioid agonist therapy in the past six months was significantly associated with vaccination.

CONCLUSIONS

Influenza vaccine uptake was lower among PWID than the Australian general population. Provision of the vaccine at services commonly accessed by PWID may increase uptake.

Tuberculosis as a Risk Factor for 1918 Influenza Pandemic Outcomes

Tuberculosis (TB) mortality declined after the 1918 pandemic, suggesting that influenza killed those who would have died from TB. Few studies have analyzed TB as a direct risk factor for 1918 influenza morbidity and mortality by age and sex. We study the impacts of TB on influenza-like illness (% of population sick) and case fatality (% of cases dying) by age and sex through case-control comparisons of patients (N = 201) and employees (N = 97) from two Norwegian sanatoriums. Female patients, patients at Landeskogen sanatorium, and patients aged 10–39 years had significantly lower morbidity than the controls. None of the 62 sick employees died, while 15 of 84 sick patients did. The case-control difference in case fatality by sex was only significant for females at Lyster sanatorium and females at both sanatoriums combined. Non-significant case-control differences in case fatality for males were likely due to small samples. Patients 20–29 years for both sexes combined at Lyster sanatorium and at both sanatoriums combined, as well as females 20–29 years for both sanatoriums combined, had significantly higher case fatality. We conclude that TB was associated with higher case fatality, but morbidity was lower for patients than for employees. The results add to the study of interactions between bacterial and viral diseases and are relevant in preparing for pandemics in TB endemic areas.

Active opioid use does not attenuate the humoral responses to inactivated influenza vaccine

BACKGROUND

Influenza vaccination is recommended for vulnerable individuals, including active drug users, to prevent influenza complications and decrease influenza spread. Recent studies suggest that opioids negatively regulate immune responses in experimental models, but the extent to which opioid use will affect the humoral responses to influenza vaccine in humans is unknown. This information is critical in maximizing vaccination efforts.

OBJECTIVE

To determine whether there is a difference in antibody response after influenza vaccination in heroin or methadone users compared to control subjects.

METHODS

We studied active heroin users, subjects on methadone maintenance treatment (MMT) and subjects that did not use any drugs before and 1 and 4 weeks after vaccination with trivalent influenza vaccine (TIV). We measured hemagglutination inhibition and microneutralization titers, and we compared geometric mean titers (GMT), and rates of seroprotection and seroconversion for each of the vaccine strains among the 3 groups of subjects.

RESULTS

Heroin users, subjects on MMT and non-user controls mount a similarly robust serologic response to TIV. GMT and rates of seroprotection and seroconversion were not significantly different among groups.

CONCLUSION

Our results suggest that opioid use do not significantly alter antibody responses to influenza vaccine supporting the vaccination effort in these populations.

Efficacy of influenza vaccination in patients with cirrhosis and inactive carriers of hepatitis B virus infection

BACKGROUND

Influenza can causes morbidity and mortality that are greatly enhanced in patients with underlying chronic diseases such as Cirrhotic patients. This study was performed to assess the immunogenicity of Influenza vaccination in patients with cirrhosis and inactive carriers of Hepatitis B virus infection.

METHODS

In this clinical study 93 enrolled subjects divided into 3 groups: Cirrhotic (N=28), Inactive carriers of Hepatitis B (N=31) and subjects (N=34). All the participants were vaccinated by Influenza vaccine (Influvac®). Serum samples were taken before and 4 weeks after vaccination and the Humoral Immunogenicity was assessed by the Hemagglutination Inhibition (HI) test.

RESULTS

Four weeks after vaccination, seroconversion rates of vaccine strains ranged between 71.4% and 100% in Group 1, 70.6% and 94.1% in Group 2, and 58.1% and 80.7% in Group 3. No significant differences were seen in the rates of Seroconversion and antibody Geometric Mean Titers (GMTs) against Influenza A (H1N1 and H3N2) vaccine components in the three groups (P>0.05).The rates of Seroconversion and antibody GMTs against Influenza B vaccine component were significantly higher in Cirrhotic and inactive carriers of Hepatitis B than healthy subjects (P<0.005). No significant (P>0.05) differences in the rates of Seroprotection were observed within the three groups. Antibody GMTs against all three strains of Influenza vaccine increased significantly (P<0.001) after vaccination in three groups.

CONCLUSION

Influenza vaccination is effective in Cirrhotic patients and inactive carriers of Hepatitis B as well as healthy individuals. It means that vaccination should be considered in such patients in order to reduce the morbidity and mortality of Influenza.

Rates and correlates of influenza vaccination among HIV-infected adults in the HIV Outpatient Study (HOPS), USA, 1999-2008

BACKGROUND

We sought to describe rates of vaccination among HIV-infected adults in care and identify factors associated with vaccination.

METHODS

Using data abstracted from medical records of participants in the HIV Outpatient Study (HOPS) during 8 influenza seasons (1999-2008) and negative binomial models with generalized estimating equation methods, we examined factors associated with increased prevalence of annual influenza vaccination.

RESULTS

Among active patients, 25.8% to 43.3% were vaccinated for influenza each year (annual mean=35%, test for trend p=0.71). Vaccination rates peaked in October and November of each season and decreased sharply thereafter. In multivariable analysis, patients who were male (67.2%), non-Hispanic white (70%) or Hispanic (66%), had lower HIV viral loads (73.5%), were prescribed antiretroviral treatment (72.7%), or had a greater number of clinical encounters per year (86.7%) were more likely to receive influenza vaccination.

DISCUSSION

The decreased likelihood of vaccination among women and non-Hispanic black patients suggests the need for focused efforts to reduce disparities. Increasing patient and clinician education on the importance of universal vaccination, and ensuring that vaccination activities continue in HIV clinics during the later months of the influenza season may improve influenza vaccine coverage.

Protecting vulnerable populations from pandemic influenza in the United States: a strategic imperative

Protecting vulnerable populations from pandemic influenza is a strategic imperative. The US national strategy for pandemic influenza preparedness and response assigns roles to governments, businesses, civic and community-based organizations, individuals, and families. Because influenza is highly contagious, inadequate preparedness or untimely response in vulnerable populations increases the risk of infection for the general population. Recent public health emergencies have reinforced the importance of preparedness and the challenges of effective response among vulnerable populations. We explore definitions and determinants of vulnerable, at-risk, and special populations and highlight approaches for ensuring that pandemic influenza preparedness includes these populations and enables them to respond appropriately. We also provide an overview of population-specific and cross-cutting articles in this theme issue on influenza preparedness for vulnerable populations.