No Further Testing Required After 91 Days
Your negative HIV Ag/Ab Combo ECLIA tests at 63 and 91 days post-exposure are conclusive, and no additional testing is needed. 1, 2
Why Your Results Are Definitive
The most recent CDC guidelines (2025) establish that final, conclusive HIV testing should occur at 12 weeks (84 days) post-exposure using laboratory-based Ag/Ab testing. 1, 2 Your 91-day test exceeds this threshold and definitively rules out HIV infection from your exposure.
Key Timeline Considerations
Fourth-generation Ag/Ab Combo tests (like ECLIA) are considered conclusive after 12 weeks of potential exposure, accounting for both the window period of the test and antiretroviral washout time if you took post-exposure prophylaxis. 1, 2
Your 63-day test already provided strong reassurance, as most laboratory-based Ag/Ab tests detect HIV approximately 18-45 days post-infection. 2
The 91-day test provides the definitive answer, occurring well beyond the 12-week (84-day) conclusive testing window recommended by CDC. 1, 2
Understanding Test Sensitivity
Fourth-generation Ag/Ab Combo tests detect both HIV p24 antigen and HIV antibodies (IgM and IgG), making them highly sensitive for detecting infection. 1
These tests have greater than 98% sensitivity and specificity for HIV when used at appropriate timepoints. 3
Research shows that Ag/Ab Combo assays detect approximately 82% of acute HIV infections and nearly all established infections. 4, 5
By 91 days post-exposure, even the rare cases that might be missed during acute infection would have developed detectable antibodies. 2, 5
Important Caveats
The only scenario requiring additional consideration would be if you:
Took antiretroviral medications (PEP or PrEP) during or after your exposure, as these can suppress viral load and delay antibody formation. 1, 2, 6 However, even with PEP, the 12-week post-exposure timepoint accounts for antiretroviral washout. 1, 2
Had additional HIV exposures after your initial exposure, which would restart the testing timeline. 1
Received long-acting injectable PrEP (cabotegravir) in the past year, which might warrant nucleic acid testing (NAT) in addition to Ag/Ab testing. 1, 6
Clinical Bottom Line
Your two negative tests using a highly sensitive fourth-generation method, with the final test at 91 days, provide definitive evidence that you did not acquire HIV from your exposure. 1, 2 No further HIV testing related to this exposure is necessary unless you have had subsequent exposures or took antiretroviral medications that were not disclosed.