Sunday House Call, #670, October 7, 2018: The lifespan of the flu shot
Topics today include:
Answering a question of about whether the flu vaccine effectiveness wanes during the season and if so do you require a booster?*
Your calls about:
- chronic couch
- A bump near the ear
- Second-hand exposure to marijuana in apartment buildings
- Management of a Baker’s Cyst
- After care management of incisions sites from laparoscopic removal of the gallbladder (cholecystectomy)
*Waning immunity after a flu shot is a very interesting topic. During News and Views’ Wednesday House Call show I did not have the information on hand to accurately answer the question. I found the answer from up-to-date.com.
I include a passage from the article in uptodate.com that explains that despite some waning immunity, the rate of decline is not enough to reduce a person’s immune response and will cover them throughout flu season.
Waning of antibodies and effectiveness — There has been concern that the response to annual vaccination might attenuate over time, particularly in older individuals, although the data have been variable.
A 2008 literature review that included studies of individuals >60 years old found that, after influenza vaccination, seroprotection was maintained for at least four months (and often for longer) in all eight studies that assessed antibody responses to the H3N2 component and in five of seven studies that assessed responses to the H1N1 and B components [127]. Following successful immunization, seroprotection rates of 70 to 100 percent were maintained not just at four months (two studies) but also at five months (two studies) and at >6 months (four studies) for the H3N2 and H1N1 influenza A vaccine components. Seroprotection rates were less consistent for the influenza B vaccine component.
A subsequent study showed a decline in antibody titers six months after vaccination in individuals ≥65 years of age, although the titers still met the levels considered adequate for protection [128]. Low prevaccination HAI titer (<1:40) and advanced age were associated with early decline of HAI titers, falling below presumed seroprotective levels around six months following vaccination. In a 2018 meta-analysis of 14 case-control studies, a significant decline in vaccine effectiveness (VE) occurred in the first six months following influenza vaccination [129]. The decline was more pronounced for influenza A H3N2 and influenza B viruses than for influenza A H1N1 virus and was faster among older individuals in the two studies that included a significant proportion of older adults.
In contrast, among healthy adults 18 to 49 years of age participating in a randomized trial of influenza vaccination, hemagglutination inhibition and neuraminidase inhibition titers decreased slowly over 18 months; a twofold decrease in antibody titer was estimated to take >600 days [130]. In another study in healthy adults 18 to 49 years of age, inactivated influenza vaccine efficacy decreased slowly over the course of the influenza season and remained efficacious for the majority of the season [131].
128. Song JY, Cheong HJ, Hwang IS, et al. Long-term immunogenicity of influenza vaccine among the elderly: Risk factors for poor immune response and persistence. Vaccine 2010; 28:3929.
129. Young B, Sadarangani S, Jiang L, et al. Duration of Influenza Vaccine Effectiveness: A Systematic Review, Meta-analysis, and Meta-regression of Test-Negative Design Case-Control Studies. J Infect Dis 2018; 217:731.
130. Petrie JG, Ohmit SE, Johnson E, et al. Persistence of Antibodies to Influenza Hemagglutinin and Neuraminidase Following One or Two Years of Influenza Vaccination. J Infect Dis 2015; 212:1914.
131. Petrie JG, Ohmit SE, Truscon R, et al. Modest Waning of Influenza Vaccine Efficacy and Antibody Titers During the 2007-2008 Influenza Season. J Infect Dis 2016; 214:1142.