You may have been exposed. Here's how to think about it clearly.

The four-factor exposure model

When BioShield AI weighs an exposure, it looks at four factors:

1. Proximity. Close, sustained, face-to-face matters far more than passing or outdoor contact.
2. Duration. Minutes add up. A 15-minute conversation inside is more meaningful than a two-second elevator encounter.
3. Ventilation. Outdoors and well-ventilated spaces reduce risk substantially. Crowded, stale indoor air does the opposite.
4. Vulnerability. Your own health status — and who lives with you — shifts how conservatively you should act.

What to do after close-contact exposure

A sick friend, coworker, roommate, or family member has tested positive or is clearly symptomatic with a contagious illness.

If you feel fine

• Begin a monitoring window based on the likely illness (commonly 2–10 days for most respiratory viruses; check specific guidance for the pathogen).
• Take note of your baseline: temperature, energy, breathing, any lingering conditions.
• If you have vulnerable household members, consider masking indoors and minimizing shared meals for the first several days.
• Testing too early is often a waste — consider testing 3–5 days after exposure, or sooner if symptoms develop.

If symptoms appear

• Don't power through it — isolate as soon as it's practical.
• Test if it will meaningfully change what you do (e.g., antiviral eligibility, household isolation, time off work).
• Match your action to your household: higher-vulnerability = faster escalation.

Exposure at work, school, or public events

This is the most common category — and typically the lowest-urgency category. Mass workplace or school exposures with no close sustained contact rarely warrant major action.

• If you were in the same room as someone symptomatic but never close or prolonged: baseline monitoring for 3–5 days is usually enough.
• If you shared a meal, a ride, or a small meeting with a sick person: treat it more like a close-contact exposure.
• Kids in school spreading illness is normal — it is the single most common pattern our users describe. Household preparation (see our Preparedness Hub) usually matters more than reacting to any single exposure.

Household exposure planning

When someone in your home is sick, the default assumption is that the rest of the household has been exposed. The goal shifts from prevention to reducing transmission while still caring for the sick person.

Reasonable household protocol

• Designate a "sick room" if possible, and ideally a separate bathroom.
• The sick person wears a well-fitting mask in shared spaces when feasible.
• Open windows where weather allows; upgrade HVAC filter to MERV-13 if it fits your system.
• Wipe down high-touch surfaces daily: doorknobs, faucets, remotes, phones.
• Caregiver ideally is the lowest-risk person in the household.
• Monitor vulnerable household members more closely.

Exposure after flights, travel, or cruise trips

Travel exposure is less about any single seatmate and more about cumulative load: airports, planes, hotels, restaurants, transit. A reasonable default is:

• Monitor your baseline for 3–7 days after returning.
• If you've been in a dense outbreak zone (e.g., a cruise with a known surge), tighten the window and be quicker to test.
• Consider masking on your return-leg flight if you have a vulnerable household member.
• Don't schedule high-stakes events with vulnerable relatives in the first few days post-travel if you can avoid it.

What to watch for after possible exposure

You don't need to obsessively self-check. A once-a-day, thirty-second read is enough. Watch for:

• Any new respiratory symptom: cough, congestion, sore throat, shortness of breath.
• Fever, chills, body aches, or unusual fatigue.
• GI symptoms (nausea, diarrhea), particularly if they appear with fever.
• Loss of taste or smell.
• Anything "not quite right" that is unusual for you — pattern breaks matter more than any single symptom.

How long to monitor

Windows vary by pathogen, but for most common respiratory illnesses:

• Influenza: typically 1–4 days from exposure to symptom onset.
• Common cold viruses: usually 1–3 days.
• COVID-19 (modern variants): most symptoms appear within 2–5 days, occasionally up to 10–14.
• RSV: typically 4–6 days.
• Norovirus / GI viruses: often 12–48 hours.

If nothing has appeared within the upper end of the relevant window, your exposure is effectively "cleared" from a monitoring standpoint.

This hub is educational guidance and is not medical advice. Specific illnesses and individual health factors may shift the right action. For severe or unusual symptoms, don't wait — seek urgent care.