[Immunogenicity and safety of the influenza vaccine, in a population older than 55-years in Mexico].
OBJECTIVE
To confirm the immunogenicity and tolerance of the inactivated, fractionated, and purified influenza vaccine, in a Mexican adult population aged 55 and older, medically served at a Petróleos Mexicanos Hospital (Pemex, Mexican Oil Company).


METHODS
The study was conducted between November and December, 2000, among ninety adult subjects aged 55 years and older who were seen at the Hospital Central Sur Pemex. The primary endpoints regarding immunogenicity were the percentage of individuals with protective antibodies targeting hemagglutinins higher than or equal to 1:40, and the percentage of subjects who seroconverted as measured by a four-fold increase in protective antibody production. Secondary endpoints included the frequency of local and systemic reactions to the vaccine. An additional criterion that was evaluated included antigen-antibody affinity assays to measure the polyclonal antibody response to the vaccine and the specific generation of high-affinity antibodies to viral proteins, before and after vaccination.


RESULTS
The antibody protection rate was 95.6% against the HINI strain, 98.9% against the H3N2 strain, and a 100% against the B/Yamanashi strain. Seroconversion to the HINI strain was elicited in 74.4% of subjects, to the H3N2 strain in 88.9%, and to the B/Yamanashi strain in 82.2%. Eighteen (20%) subjects developed local reactions; 17 (18.8%) developed a systemic reaction post vaccination at day 5 and nine subjects (10%) at day 28. Local reactions consisted of pain in 10 (11.1%) subjects, redness in 8 (8.8%), and induration in 6 (6.6%). General malaise, headache, and fever were identified in 10, 8.8, and 0% of subjects, respectively, at day 5, and in 4.4, 6.6, and 0%, respectively, at day 28.


CONCLUSIONS
Influenza vaccine was highly immunogenic in a healthy Mexican adult population aged 55 years and older. The generation of high-affinity antibodies to the virus after vaccination was also demonstrated. Local and systemic adverse reactions to the vaccine identified in our study were similar to those in previous reports. The results of this study can be extrapolated to other health institutions serving this adult population to increase influenza vaccine coverage rates.
Ayala-Montiel
Octavio
O
Hospital Central Sur, Petróleos Mexicanos (Pemex), México, DF, México.
Mascareñas
César
C
García-Hernández
Delfino
D
Rendón-Muñiz
Jorge
J
López
Irma
I
Felipe Montaño
Luis
L
Zenteno
I
I
Franco-Paredes
C
C
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000009:adverse effects / Q000276:immunology*; D008297:Male; D008800:Mexico; D008875:Middle Aged; D011446:Prospective Studies
D007252:Influenza Vaccines