Breakthrough infection
A breakthrough infection is a case of illness in which a vaccinated individual becomes infected with the illness, because the
Causes of breakthrough infections include biological factors in the recipient, improper administration or storage of vaccines, mutations in viruses, blocking antibody formation, and other factors. For these reasons, vaccines are rarely 100% effective. A 2021 study found the common flu vaccine provided immunity to the flu in 58% of recipients.[6] The measles vaccine fails to provide immunity to 2% of children that receive the vaccine. However, if herd immunity exists, it typically prevents individuals who are ineffectively vaccinated from contracting the disease.[7] Accordingly, herd immunity reduces the number of breakthrough infections in a population.[8]
By disease
Varicella
The varicella vaccine is 85% effective at preventing varicella (chickenpox) infection.[9] However, 75% of individuals that are diagnosed with breakthrough varicella exhibit milder symptoms than individuals that are not vaccinated.[5] These individuals with mild varicella have low fevers, fewer than 50 lesions on their skin, and a maculopapular rash. In contrast, unvaccinated individuals typically have a fever of 102, 200-500 skin lesions, and macules (lesions that are not elevated) evolve to papules and vesicular lesions.[5][10] Additionally, infection in unvaccinated individuals tends to last for a longer period of time than in individuals who have been vaccinated.[5]
The majority of cases of breakthrough varicella are attributed to the failure of an individual to uptake[clarification needed] the varicella vaccine.[9] Therefore, to prevent breakthrough infections, it is proposed that children receive a second dose of varicella vaccine less than a year after getting their first dose.[9]
Mumps
The mumps vaccine is a component of the Measles, Mumps and Rubella vaccine (MMR).[11] The mumps vaccine, specifically, is 88% effective at preventing mumps.[12] Individuals with breakthrough cases of mumps have fewer serious complications from the infections as compared to individuals unvaccinated for mumps.[13] These complications include the development of aseptic meningitis and encephalitis.[13]
The cause of breakthrough mumps is not currently completely understood. Evolution of the virus (antigenic drift) is thought to explain the majority of breakthrough cases.[13] Other theories suggest that memory T lymphocytes play a role in the development of breakthrough infections.[13]
Hepatitis B
Breakthrough cases of Hepatitis B are primarily attributed to mutations in the Hepatitis B virus (HBV) that make HBV surface proteins unrecognizable to antibodies produced from the HBV vaccine.[14][15][16] Viruses with such mutations are called "vaccine escape mutants". Breakthrough infections may also be caused by delayed vaccination, immunosuppression, and maternal viral load.[15] It is possible for an individual to have breakthrough infection of HBV but be asymptomatic.[14]
COVID-19
In April 2021, scientists reported that in a
Characteristics
Age
As a person ages, their immune system undergoes a series of changes, in a process referred to as
Indeed, vaccines, including the influenza vaccine,
Antibody interference
The presence of
In most infants, maternal antibodies disappear 12–15 months after birth, so vaccines administered outside this window are not compromised by maternal antibody interference.[8]
Longevity of memory B cells
When an individual is vaccinated against a disease, the individual's immune system is triggered and memory B cells store the specific antibody response.[8] These cells remain in circulation until the pathogen infection is cleared. Because the telomeres in genes degenerate after each successive cell division, lymphocytes, including memory B cells are not capable of proliferating indefinitely.[28] Typically, the cells live for multiple decades, but there is variation in the longevity of these cells depending on the type of vaccine they were stimulated with and the vaccine dosage.[32] The reason for the differences in the longevity of memory B cells is currently unknown. However, it has been proposed that the differences in memory B cell longevity are due to the speed at which a pathogen infects the body and, accordingly, the number and type of cells involved in the immune response to the pathogen in the vaccine.[33]
Virus evolution
When a person is vaccinated, their immune system develops antibodies that recognize specific segments (epitopes) viruses or viral-induced proteins. Over time, however, viruses accumulate genetic mutations which can impact the 3D structure of viral proteins.[34] If these mutations occur in sites that are recognized by antibodies, the mutations block antibody binding which inhibits the immune response.[35] This phenomenon is called antigenic drift. Breakthrough infections of Hepatitis B and mumps are partially attributed to antigenic drift.[13][15]
Vaccine quality and administration
Vaccines may fail to provide immunity if the vaccine is of poor quality when administered. A vaccine loses potency if it is stored at the incorrect temperature or if it is kept after the expiration date.[36] Similarly, appropriate vaccine dosage is essential to ensuring immunity. Vaccine dosage is dependent on factors including a patient's age and weight.[36] Failure to account for these factors can lead to patients receiving an incorrect amount of vaccination. Patients that receive a lower dose than recommended of a vaccine do not have an adequate immune response to the vaccine to ensure immunity.[32]
In order for a vaccine to be effective, an individual must respond to the pathogens in a vaccine through the adaptive branch of the immune system and that response must be stored in an individual's immunological memory.[8] It is possible for an individual to neutralize and clear a pathogen through the humoral response without activating the adaptive immune response.[8] Vaccines with weaker or fewer strains of a pathogen, as is the case when a vaccine is of poor quality when administered, may primarily elicit the humoral response, and, thus, fail to ensure future immunity.[8]
References
- ^ CDC (2020-02-11). "COVID-19 Vaccination". Centers for Disease Control and Prevention. Retrieved 2022-01-06.
- ^ "Factsheet for health professionals". ecdc.europa.eu. Archived from the original on 2017-02-24. Retrieved 2017-02-24.
- ^ "Chickenpox | Clinical Overview | Varicella | CDC". www.cdc.gov. Retrieved 2017-02-24.
- ^ "Use of Antivirals | Health Professionals | Seasonal Influenza (Flu)". CDC.gov. Retrieved 2017-02-24.
- ^ a b c d "Chickenpox (Varicella)". Center for Disease Control and Prevention. 1 July 2016.
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- ^ ISBN 978-14292-1919-8.
- ^ PMID 24757524.
- ^ "Pinkbook | Varicella | Epidemiology of Vaccine Preventable Diseases | CDC". www.cdc.gov. Retrieved 2017-02-17.
- ^ "Factsheet for health professionals". ecdc.europa.eu. Archived from the original on 2017-02-24. Retrieved 2017-02-17.
- ^ "Mumps | Cases and Outbreaks | CDC". www.cdc.gov. Retrieved 2017-02-17.
- ^ PMID 25951183.
- ^ S2CID 23463146.
- ^ PMID 20516566.
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- ^ Howard, Jacqueline. "Only 2 'breakthrough' infections among hundreds of fully vaccinated people, new study finds". CNN. Retrieved 11 May 2021.
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- ^ Gilbert, Ben; Brubeck, Hilary (15 April 2021). "CDC: 5,800 COVID-19 infections, 74 deaths in the more than 75 million fully vaccinated people". Business Insider. Retrieved 18 April 2021.
- ^ Krieger, Lisa M. (15 April 2021). "COVID vaccines: The mystery of "breakthrough" infections after shots - CDC reports 5,800 COVID-19 infections, 74 deaths in fully vaccinated people". The Mercury News. Retrieved 18 April 2021.
- Orange County Register. Retrieved 18 April 2021.
- ^ Masson, Gabrielle (15 April 2021). "5,800 COVID-19 infections detected among 77 million fully vaccinated people: CDC". Beckers Hospital Review. Retrieved 18 April 2021.
- ^ May, Brandon (15 April 2021). "COVID-19 Infection After Vaccine is Rare But Possible, CDC Says". BioSpace. Retrieved 18 April 2021.
- ^ Whelan, Robbie (15 April 2021). "CDC Identifies Small Group of Covid-19 Infections Among Fully Vaccinated Patients - Incidence is rare, occurring in only 0.008% of cases and in line with expectations". The Wall Street Journal. Retrieved 18 April 2021.
- ^ Wadman, Meredith (4 August 2021). "What does the Delta variant have in store for the United States? We asked coronavirus experts". Science News. Retrieved 2021-08-23.
In the Massachusetts outbreak, fully vaccinated people accounted for 74% of nearly 469 COVID-19 cases.
- S2CID 236935466.
- ^ Gabashvili IS The Incidence and Effect of Adverse Events Due to COVID-19 Vaccines on Breakthrough Infections: Decentralized Observational Study With Underrepresented Groups JMIR Form Res 2022;6(11):e41914 doi:10.2196/41914 PMID: 36309347 PMCID: 9640199
- ^ PMID 23584248.
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- ^ a b "Vaccine Effectiveness - How Well Does the Flu Vaccine Work? | Seasonal Influenza (Flu) | CDC". www.cdc.gov. Retrieved 2017-02-23.
- ^ PMID 26256526.
- ^ ISBN 9781455700905.
- ^ "Top 20 Questions about Vaccination | History of Vaccines". www.historyofvaccines.org. Retrieved 2017-02-15.
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- ^ "Viruses and Evolution | History of Vaccines". www.historyofvaccines.org. Retrieved 2017-02-11.
- ^ a b Hamborsky, Jennifer; Kroger, Andrew; Wolfe, Charles (2013). Epidemiology and Prevention of Vaccine Preventable Diseases. Washington D.C.: Center for Disease Control and Prevention.