Post-exposure time to vaccinate

Smallpox Sense: Vaccine Has Small But Significant Risks

In addition, it is known that individuals exposed to smallpox can be protected against illness if they are vaccinated within a few days after exposure. Therefore, we have no need to expose the entire U.S. population to the risks of smallpox vaccination with the current vaccine.

Super smallpox Saturdays?

Smallpox patients can be very sick as soon as a week after infection with the virus but – and this is vital – they don't spread the virus until after they're sick in bed and the spots on the skin start to develop...If smallpox does break out, vaccination within four days after exposure can prevent or significantly reduce the severity of illness.

Smallpox Contingency Plan Revealed

It takes fairly close proximity, within about six feet of a person suffering the characteristic rash, to breathe in the smallpox virus and catch the disease. Quickly vaccinating those who live with or work around a patient is protective. 

World Health Body Rules Out Mass Smallpox Jabs

Another argument against mass inoculation is that the smallpox vaccine can be administered after the disease has been contracted, provided it is detected quickly, WHO head of communicable diseases David Heymann said.

The incubation period for smallpox is seven to 14 days and the vaccine is effective if given within four days of infection.

Vaccinia (Smallpox) Vaccine: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2001

Postrelease Vaccination

If an intentional release of smallpox (variola) virus does occur, vaccinia vaccine will be recommended for certain groups. Groups for whom vaccination would be indicated include

• persons who were exposed to the initial release of the virus;
• persons who had face-to-face, household, or close-proximity contact (<6.5 feet or 2 meters) (84) with a confirmed or suspected smallpox patient at any time from the onset of the patient's fever until all scabs have separated;
• personnel involved in the direct medical or public health evaluation, care, or transportation of confirmed or suspected smallpox patients;
• laboratory personnel involved in the collection or processing of clinical specimens from confirmed or suspected smallpox patients; and
• other persons who have an increased likelihood of contact with infectious materials from a smallpox patient (e.g., personnel responsible for medical waste disposal, linen disposal or disinfection, and room disinfection in a facility where smallpox patients are present).

Using recently vaccinated personnel (i.e., <3 years) for patient care activities would be the best practice. However, because recommendations for routine smallpox vaccination in the United States were rescinded in 1971 and smallpox vaccination is currently recommended only for specific groups (see Routine Nonemergency Vaccine Use), having recently vaccinated personnel available in the early stages of a smallpox emergency would be unlikely. Smallpox vaccine can prevent or decrease the severity of clinical disease, even when administered 3--4 days after exposure to the smallpox virus (2,4,85). Preferably, healthy persons with no contraindications to vaccination, who can be vaccinated immediately before patient contact or very soon after patient contact (i.e., <3 days), should be selected for patient care activities or activities involving potentially infectious materials. Persons who have received a previous vaccination (i.e., childhood vaccination or vaccination >3 years before) against smallpox might demonstrate a more accelerated immune response after revaccination than those receiving a primary vaccination (3). If possible, these persons should be revaccinated and assigned to patient care activities in the early stages of a smallpox outbreak until additional personnel can be successfully vaccinated.