Vaccination Does Not Equal Immunization

Outbreaks of diseases occur in fully and highly vaccinated populations.  Because of incorrect dosing recommendations, waning immunity, and outright vaccine failure, many vaccinated children turn out to be as just unprotected as unvaccinated children.  It is essential to remember that just because a child is vaccinated does not mean the child is immunized.   It is therefore unfair to exercise prejudice against unvaccinated children as special public health threats when vaccinated children are often just as vulnerable to disease.

Documentation of outbreaks in fully and highly vaccinated populations

Pertussis 

"This report describes a statewide outbreak of pertussis in Vermont (1995 population: 584,771) in 1996 in a highly vaccinated population, affecting primarily school-aged children and adults, and underscores the need to include pertussis in the differential diagnosis of cough illness in persons of all ages."

-- Pertussis outbreak -- Vermont, 1996. MMWR Morb Mortal Wkly Rep 1997 Sep 5;46(35):822-6

 

"Coverage studies for pertussis vaccine in Cape Town indicated that between 81 and 93 per cent of children were fully immunized by 13 months of age...However, it was not able to prevent a moderate scale outbreak, even in the presence of high vaccination levels."

-- Strebel P, Hussey G, Metcalf C, Smith D, Hanslo D, Simpson J. An outbreak of whooping cough in a highly vaccinated urban community.  J Trop Pediatr 1991 Mar;37(2):71-6 

 

"Outbreaks [of pertussis] in highly vaccinated populations have been reported, raising the issues of vaccine efficacy, of the long-term effect of vaccines on the transmission of the disease, and of genetic selective pressure." 

--Simondon F, Guiso N.  [Genetic evolution under vaccine pressure: the Bordetella pertussis model (French title)] Bull Soc Pathol Exot 2000 Jul;93(3):202-5

Measles (Rubeola) 

"This was the largest outbreak of measles in the United States since 1996."

--Transmission of measles among a highly vaccinated school population, Anchorage, Alaska, 1998.   MMWR Morb Mortal Wkly Rep 1999 Jan 8;47(51-52):1109-11

 

"The study suggested that, within highly vaccinated populations, a proportion of individuals had measles antibody levels which may be insufficient to protect against reinfection or clinical disease."

--Cox MJ, Azevedo RS, Massad E, Fooks AR, Nokes DJ.  Measles antibody levels in a vaccinated population in Brazil.  Trans R Soc Trop Med Hyg 1998 Mar-Apr;92(2):227-30

 

"From the 1970s through early into the recent measles epidemic, the majority of measles cases were in highly vaccinated, school-age children. This was due primarily to a 1 to 5% primary measles-mumps-rubella vaccine failure rate and nonrandom mixing patterns among school-age populations."

-- Wood DL, Brunell PA.  Measles control in the United States: problems of the past and challenges for the future. Clin Microbiol Rev 1995 Apr;8(2):260-7

 

"In early 1988 an outbreak of 84 measles cases occurred at a college in Colorado in which over 98 percent of students had documentation of adequate measles immunity... As in secondary schools, measles outbreaks can occur among highly vaccinated college populations."

-- Hersh BS, Markowitz LE, Hoffman RE, Hoff DR, Doran MJ, Fleishman JC, Preblud SR, Orenstein WA. A measles outbreak at a college with a prematriculation immunization requirement. Am J Public Health 1991 Mar;81(3):360-4

 

"Despite high vaccination levels, explosive measles outbreaks may occur in secondary schools due to 1) airborne measles transmission, 2) high contact rates, 3) inaccurate school vaccination records, or 4) inadequate immunity from vaccinations at younger ages."

-- Chen RT, Goldbaum GM, Wassilak SG, Markowitz LE, Orenstein WA. An explosive point-source measles outbreak in a highly vaccinated population. Modes of transmission and risk factors for disease.  Am J Epidemiol 1989 Jan;129(1):173-82

 

"An outbreak of measles occurred in a high school with a documented vaccination level of 98 per cent."

--  Nkowane BM, Bart SW, Orenstein WA, Baltier M. Measles outbreak in a vaccinated school population: epidemiology, chains of transmission and the role of vaccine failures.  Am J Public Health 1987 Apr;77(4):434-8

 

"This outbreak demonstrates that transmission of measles can occur within a school population with a documented immunization level of 100%."

--  Measles outbreak among vaccinated high school students--Illinois.  MMWR Morb Mortal Wkly Rep 1984 Jun 22;33(24):349-51

 

"Eighty-seven laboratory-confirmed or clinically confirmed cases of measles were identified...The measles vaccination rate was 94.2%, and 10% of the students had received two doses of measles vaccine before the outbreak."
-- Sutcliffe PA, Rea E.  Outbreak of measles in a highly vaccinated secondary school population.  CMAJ 1996 Nov 15;155(10):1407-13.
 

"However, the extent of measles transmission among highly vaccinated school-age populations suggests that additional strategies, such as selective or mass revaccination, may be necessary to prevent such outbreaks."
-- Markowitz LE, Preblud SR, Orenstein WA, Rovira EZ, Adams NC, Hawkins CE, Hinman AR.  Patterns of transmission in measles outbreaks in the United States, 1985-1986.  N Engl J Med 1989 Jan 12;320(2):75-81. 

Mumps 

"The overall attack rate is the highest reported to date (and to our knowledge) for a population demonstrating virtually complete mumps vaccine coverage."

--Cheek JE, Baron R, Atlas H, Wilson DL, Crider RD Jr.  Mumps outbreak in a highly vaccinated school population. Evidence for large-scale vaccination failure.  Arch Pediatr Adolesc Med 1995 Jul;149(7):774-8.

 

"Vaccine failure accounted for a sustained mumps outbreak in a highly vaccinated population. Most mumps cases were attributable to primary vaccine failure. It is possible that waning vaccine-induced immunity also played a role."

--  Briss PA, Fehrs LJ, Parker RA, Wright PF, Sannella EC, Hutcheson RH, Schaffner W.  Sustained transmission of mumps in a highly vaccinated population: assessment of primary vaccine failure and waning vaccine-induced immunity.  J Infect Dis 1994 Jan;169(1):77-82.

 

"From October 1988 to April 1989, a large mumps outbreak occurred in Douglas County, Kansas. Of the 269 cases, 208 (77.3%) occurred among primary and secondary school students, of whom 203 (97.6%) had documentation of mumps vaccination. "
-- Hersh BS, Fine PE, Kent WK, Cochi SL, Kahn LH, Zell ER, Hays PL, Wood CL.  Mumps outbreak in a highly vaccinated population.  J Pediatr 1991 Aug;119(2):187-93

Chickenpox 

"A chickenpox outbreak occurred in a school in which 97% of students without a prior history of chickenpox were vaccinated."
--Barna D. Tugwell, MD*, Lore E. Lee, MPH, Hilary Gillette, RN, MPH, Eileen M. Lorber, MD, Katrina Hedberg, MD, MPH and Paul R. Cieslak, MD.  Pediatrics, Vol. 113 No. 3 March 2004, pp. 455-459.

 

"In conclusion, we found varicella outbreaks in CCCs [child care centers] with both high and low vaccination coverage." 

--Buchholz U, Moolenaar R, Peterson C, Mascola L.  Varicella outbreaks after vaccine licensure: should they make you chicken?  Pediatrics 1999 Sep;104(3 Pt 1):561-3 

Influenza 

"An outbreak of influenza A (H3N2) occurred aboard a U.S. Navy ship in February 1996, despite 95% of the crew's having been appropriately vaccinated."

--Earhart KC, Beadle C, Miller LK, Pruss MW, Gray GC, Ledbetter EK, Wallace MR.  Outbreak of influenza in highly vaccinated crew of U.S. Navy ship.  Emerg Infect Dis 2001 May-Jun;7(3):463-5.