Aa
updated on Window Period Worry Wells
Preamble
On 16 November, 2007 , the combined National HIV
Epidemiology and Laboratory Consensus Meeting (40 to 50
participants) considered the scientific evidence for defining the
period of time following exposure and infection with HIV and the
generation of detectable antibodies by the infected person, i.e., the
so-called "window period". The following is the consensus
statement that was reached following consideration of the
available information and lengthy discussion.
Studies of the natural history of HIV infection have defined a
period of time following exposure and infection when the infected
person has not yet generated a detectable antibody response.
During this time, current antibody tests cannot detect the presence
of the infection in spite of recent improvements in sensitivity.
Studies to evaluate the length of the window period have
several limitations.
· Often little information is available on the precise time of the
exposure (except in some situations such as occupational
exposure to HIV-infected blood-body fluids due to a needle
stick), the occurrence of infection, or the period of
infectiousness.
· A limited number of scientific studies over time have used 1st,
2nd, and 3rd generation HIV antibody tests to determine the
duration of the window period. The increased sensitivity of 3rd
generation tests has reduced the time duration of the window
period(1).
· The total number of patients studied worldwide in retrospective
blood transfusion-related studies, prospective seroconversion
studies, or as individual case reports probably does not exceed
300.
· There is considerable uncertainty about the nature of the
distribution of window periods given the large amount of
variability in the immune response among infected persons.
· There are no reliable data on whether or not there is a significant
"tail" representing persons with very long window periods,
extending well beyond the estimated mean time to seroconvert.
To date, reports of excessively long incubation periods, have
been refuted and withdrawn by the original authors(2,3).
However, the possibility still exists that a few individuals may
seroconvert well beyond the estimated mean time. The small
number of persons studied created some uncertainty regarding
the mean of the distribution as well.
· There are anecdotal and case reports in the scientific literature
reporting window periods that extend beyond 3 months
following exposures. However, there is usually a lack of
information regarding the viral inoculum, the type of virus, the
type and timing of the exposure, the route of transmission, etc.,
to enable accurate interpretation of these reports.
Newly developing technologies to detect the presence of HIV
directly without reliance on the development of antibodies are not
yet accessible for general use to shorten the window period from
weeks to perhaps days. Until newer technologies are available,
antibody testing will continue to be the principal approach for
diagnosing HIV infection.
The Canadian Medical Association’s statement on the HIV
Window Period has defined it as follows:
"The enzyme-linked immunosorbent assay (ELISA) rarely fails
to detect serum HIV antibodies when they are present. A negative
ELISA indicates that HIV antibodies were not detected. This
means that either the patient is not infected or the patient is in the
"window period" between HIV infection and the beginning of
antibody production. This window period may last up to 6 months,
although 95% of adults will seroconvert (develop HIV antibodies)
within 3 months."(4)
Contained in this FAX issue: (No. of pages: 5) Official page numbers:
CONSENSUS STATEMENT REGARDING THE HIV "WINDOW PERIOD" . . . . . . . . . F-1 213 – 215
SURROGATE MARKERS OF HIV INFECTION . . . . . . . . . . . . . . . . . F-2 215 – 216
INTERIM GUIDELINES FOR THE TREATMENT OF GONOCOCCAL AND CHLAMYDIAL INFECTIONS . F-3 216 – 220
On 16 November, 2007 , the combined National HIV
Epidemiology and Laboratory Consensus Meeting (40 to 50
participants) considered the scientific evidence for defining the
period of time following exposure and infection with HIV and the
generation of detectable antibodies by the infected person, i.e., the
so-called "window period". The following is the consensus
statement that was reached following consideration of the
available information and lengthy discussion.
Studies of the natural history of HIV infection have defined a
period of time following exposure and infection when the infected
person has not yet generated a detectable antibody response.
During this time, current antibody tests cannot detect the presence
of the infection in spite of recent improvements in sensitivity.
Studies to evaluate the length of the window period have
several limitations.
· Often little information is available on the precise time of the
exposure (except in some situations such as occupational
exposure to HIV-infected blood-body fluids due to a needle
stick), the occurrence of infection, or the period of
infectiousness.
· A limited number of scientific studies over time have used 1st,
2nd, and 3rd generation HIV antibody tests to determine the
duration of the window period. The increased sensitivity of 3rd
generation tests has reduced the time duration of the window
period(1).
· The total number of patients studied worldwide in retrospective
blood transfusion-related studies, prospective seroconversion
studies, or as individual case reports probably does not exceed
300.
· There is considerable uncertainty about the nature of the
distribution of window periods given the large amount of
variability in the immune response among infected persons.
· There are no reliable data on whether or not there is a significant
"tail" representing persons with very long window periods,
extending well beyond the estimated mean time to seroconvert.
To date, reports of excessively long incubation periods, have
been refuted and withdrawn by the original authors(2,3).
However, the possibility still exists that a few individuals may
seroconvert well beyond the estimated mean time. The small
number of persons studied created some uncertainty regarding
the mean of the distribution as well.
· There are anecdotal and case reports in the scientific literature
reporting window periods that extend beyond 3 months
following exposures. However, there is usually a lack of
information regarding the viral inoculum, the type of virus, the
type and timing of the exposure, the route of transmission, etc.,
to enable accurate interpretation of these reports.
Newly developing technologies to detect the presence of HIV
directly without reliance on the development of antibodies are not
yet accessible for general use to shorten the window period from
weeks to perhaps days. Until newer technologies are available,
antibody testing will continue to be the principal approach for
diagnosing HIV infection.
The Canadian Medical Association’s statement on the HIV
Window Period has defined it as follows:
"The enzyme-linked immunosorbent assay (ELISA) rarely fails
to detect serum HIV antibodies when they are present. A negative
ELISA indicates that HIV antibodies were not detected. This
means that either the patient is not infected or the patient is in the
"window period" between HIV infection and the beginning of
antibody production. This window period may last up to 6 months,
although 95% of adults will seroconvert (develop HIV antibodies)
within 3 months."(4)
Contained in this FAX issue: (No. of pages: 5) Official page numbers:
CONSENSUS STATEMENT REGARDING THE HIV "WINDOW PERIOD" . . . . . . . . . F-1 213 – 215
SURROGATE MARKERS OF HIV INFECTION . . . . . . . . . . . . . . . . . F-2 215 – 216
INTERIM GUIDELINES FOR THE TREATMENT OF GONOCOCCAL AND CHLAMYDIAL INFECTIONS . F-3 216 – 220
The thread you posted to is 5 years old. You may want to start a new thread. 6 weeks is a good indication of your status, but official guidelines still recommend testing at 3 months for a conclusive result.
Because they do. The official window period is 3 months but the Elisa tests are highly reliable beginning at 4 weeks. It is always possible that someone could turn positive after 3 months, even 6 months but we all shouldnt worry about that. Dr HHH has continued to state that he has never seen a test turn positive after 6 weeks and that has been supported by other HIV specialists.
Not sure what you are trying to get out by referencing all of these statements. Whats your point!
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