CHICKEN POX PRPHYLAXIX
TYPES OF POSTEXPOSURE PROPHYLAXIS
Whether active immunization (varicella vaccine) or passive immunization (varicella specific antibodies) is offered to a susceptible person with a history of varicella exposure will depend on the host.
Who is eligible for varicella vaccine?
Active immunization with the varicella vaccine within three to five days of exposure is associated with both prevention of infection among susceptible persons and lessening of disease severity in those who do become ill .
Varicella vaccine is recommended by the ACIP for healthy, but susceptible adults and children who were exposed to varicella, who have not received the full two-dose series. Small case series have demonstrated that varicella vaccine is efficacious for postexposure prophylaxis among household contacts of index varicella cases . In one report, 18 susceptible contacts were vaccinated within three days of exposure and 19 contacts who did not receive any intervention . Clinical varicella occurred in all of the controls and in none of the vaccinated subjects.
Although most studies on the use of varicella vaccine for postexposure prophylaxis have been done in children, susceptible adults should also be offered immunization, particularly in light of the elevated risk of complicated infection in this population.
Which patients require passive immunoprophylaxis?
Varicella vaccine, which contains live attenuated virus, is generally contraindicated for immunocompromised hosts, including those receiving immunosuppressive medications. Patients with altered immunity, who cannot receive varicella vaccination, are eligible for passive immunization (eg, VariZIG). The efficacy of VariZIG is discussed below.
The ACIP recommends that the following patient groups receive immunoprophylaxis :-
●Immunocompromised patients (including those with primary and acquired immunodeficiencies)
●Persons with neoplastic disease
●Persons taking immunosuppressive therapies
In addition, because the effects of the varicella virus vaccine on the fetus are unknown, pregnant women should not be vaccinated. Passive immunoprophylaxis should be used when postexposure prophylaxis is indicated in a pregnant female. Management of varicella exposure during pregnancy is discussed in detail elsewhere. (See "Varicella-zoster virus infection in pregnancy", section on 'Post-exposure prophylaxis'.)
Passive immunoprophylaxis is not indicated in a patient with a history of two prior doses of varicella vaccine .
MD GENERAL MEDICINE