Individuals with chronic medical conditions have an increased risk for developing complications from vaccine-preventable diseases,1 and they are also at a higher risk for severe illness after infection with severe acute respiratory syndrome coronavirus 2, the virus that causes coronavirus disease 2019 (COVID-19).2 In the midst of the COVID-19 pandemic, it is important that individuals who are at higher risk for poor outcomes from infection with vaccine-preventable diseases remain up-to-date with their immunizations.3 This article focuses on vaccine recommendations for individuals with 4 of the most common chronic medical conditions: diabetes, cardiovascular disease, asthma, and chronic obstructive pulmonary disease (COPD).

Uncontrolled diabetes places patients at increased susceptibility of infection with vaccinepreventable diseases such as influenza, pneumonia, and hepatitis B virus (HBV).4,5 Poor glycemic control may increase the severity of the infection and the risk for complications, as well as morbidity and mortality in patients who become infected.6 The 2009 H1N1 influenza pandemic demonstrated the severity of influenza in patients with diabetes and a need for protection in this subgroup.4

Evidence has demonstrated the effectiveness of the seasonal influenza vaccine in reducing hospitalizations and mortality in patients with diabetes, especially among adults 65 years and older.7 Additionally, because patients with diabetes are at a greater risk of morbidity and mortality from invasive pneumococcal infections, the American Diabetes Association recommends that adult patients with diabetes are immunized against pneumococcal disease.8

Immunization against HBV is also essential for patients with diabetes. The CDC suggests that HBV infection is approximately twice as high in patients with diabetes who are 23 years and older (compared with those in this age group without diabetes).9 Patients using injectable diabetes medications and lancing devices to self-monitor blood glucose must be educated to avoid sharing devices given the high transmissibility of HBV and the stability of the virus on surfaces, even when blood is not visible.9 Given the increased risk of HBV infection in this population, patients with diabetes who are 60 years and younger should be vaccinated against HBV. Adults with diabetes who are older than 60 years of age should consider vaccination when risk factors for infection are high, such as when receiving assisted glucose monitoring at care facilities.9

Vaccination against varicella zoster virus (VZV) also should be considered for patients with diabetes.6 Emerging evidence has shown that patients with diabetes are at higher risk for both herpes zoster and postherpetic neuralgia compared with the general population.10 Postherpetic neuralgia in patients with diabetes tends to be more persistent and severe in comparison with the general population.10 Patients with diabetes who are eligible for VZV vaccination should be counseled regarding the risk and benefit of immunization.

Patients with known cardiovascular disease, such as ischemic heart disease and heart failure, are at increased risk for hospitalization and recurrent cardiac events if infected with respiratory illnesses such as influenza A or B virus or pneumococcal infection.11,12 Evidence from randomized controlled trials (RCTs) has demonstrated that the risk of hospital admission for acute myocardial infarction is 6 times greater in the first 7 days of influenza infection compared with the control interval (20.0 admissions per week vs 3.3 admissions per week).13 Furthermore, evidence from meta-analyses of RCTs has shown a significant decrease in major cardiovascular events (95 vaccinated vs 151 placebo patients developed major cardiovascular events), including cardiovascular morbidity and all-cause mortality (1.3% vaccinated vs 1.7% placebo [95% CI, 0.36-1.83; P=.61]), in patients with a cardiovascular history who received an annual influenza vaccination.12,14 The American Heart Association and The American College of Cardiology recommend vaccination against influenza with the attenuated vaccine as a secondary prevention measure for cardiovascular events in high-risk individuals (ie, those with cardiovascular conditions).12 Evidence has also demonstrated that patients with heart failure and respiratory infections, such as laboratoryconfirmed influenza, are at a higher risk for hospitalizations and increased in-hospital morbidity and mortality.15 Vaccinations for respiratory infections have demonstrated benefit in reducing morbidity and mortality in patients with heart failure and should be routinely recommended.16

Respiratory viruses, including influenza, rhinovirus, respiratory syncytial virus, and coronaviruses, have been shown to increase the risk of asthma exacerbations, even in patients with controlled asthma.17 Individuals with asthma have an increased risk of invasive infection and subsequent pneumonia after pneumococcal infection.18 Although vaccines are available for seasonal influenza virus and pneumococcal infection, more robust data is still needed to determine the efficacy of these vaccines in reducing complications associated with infection in patients with asthma.19,20 Efficacy data of seasonal influenza vaccinations have been inconclusive for indicating whether the vaccine reduces exacerbations in patients with asthma.19 The results of a systematic review of randomized placebo-controlled trials did not show any difference in the rate of asthma exacerbations with influenza vaccinations (4% reduction and 5% risk of exacerbation across 3 studies); however, the results of observational trials have shown a reduction in asthma exacerbations may occur (occurring in 39 vaccinated vs 79 unvaccinated of 122 children; risk ratio: 0.73%; 95% CI, 0.57-0.95).19-21 Extensive trials are necessary to determine the efficacy of the influenza vaccine in reducing the morbidity and mortality associated with infection in patients with asthma; however, the Global Initiative for Asthma (GINA) 2020 guideline still recommends routine vaccination against influenza for eligible individuals given the vaccine’s safety and potential efficacy.19

GINA 2020 guidelines do not recommend routine vaccination for pneumococcal infection in patients with asthma due to a lack of robust data to support efficacy in this subgroup; however, the CDC does recommend vaccination in this patient population because it offers the most protection for those who are vulnerable.19,22

Respiratory infections are the leading cause of COPD exacerbations and may have long-term deleterious effects on patients’ lungs. Efforts to reduce infection rates are paramount to reducing repeat hospitalizations, chronic bacterial colonization, morbidity, mortality, and health care utilization cost in patients with COPD.23-25 The pathophysiology of COPD lends itself to reduced immune function within the pulmonary system and an inability to adequately recover following respiratory infections.23,25 Effectiveness of influenza vaccinations in reducing negative outcomes from infection in patients with COPD is not well defined due to a lack of robust data, and although vaccination is recommended by the international Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) 2020 guidelines, vaccine efficacy remains unclear.23,26 Recent data from a prospective, multicenter, cohort study demonstrated a 38% reduction in hospitalizations in patients with COPD who received influenza vaccination compared with those who had not been vaccinated.26 GOLD 2020 guidelines highlight the reduction of serious illness and death as the efficacy end point after influenza vaccination, and, in regard to pneumococcal vaccination, the GOLD guidelines indicate that the 23-valent pneumococcal vaccine has demonstrated a reduction in community-acquired pneumonia in patients with COPD who are younger than 65 years.23 In patients with COPD who are 65 years or older, the 13-valent pneumococcal vaccine has been effective in reducing bacteremia and serious invasive pneumococcal disease.23 Both influenza vaccination and protection against pneumococcal infection are vital in the population of patients with COPD and should be recommended to all eligible individuals.

Ensuring that the public is immunized against vaccinepreventable diseases in light of the COVID-19 pandemic is of utmost importance. Stay-at-home orders have led to a reduction in regular health care office visits and, subsequently, a reduction in routine vaccinations.27 With the influenza season approaching, health care providers must reiterate the importance of receiving annual vaccinations to protect against unnecessary health care office visits, emergency department visits, and hospitalizations.27 Individuals with chronic diseases such as diabetes mellitus, cardiovascular disorders, asthma, and COPD are at high risk for COVID-19 infection and poor outcomes following infection.2 Health care providers and systems should develop mechanisms to assist high-risk individuals in receiving routine vaccinations. Drive-through clinics as well as outdoor vaccination stations may assist in maintaining social distancing standards while still providing essential services to the population.28 With the current uncertainty surrounding COVID-19, health care providers should proactively schedule immunization visits with unvaccinated patients to ensure that high-risk individuals are protected. With the influenza season fast approaching during a global pandemic, it will be of vital importance that all health care providers lead the effort in immunizing communities against vaccine-preventable diseases. 
LUMA MUNJY, PHARMD, is an assistant professor of pharmacy practice at the Chapman University School of Pharmacy in Irvine, California.

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