When you’re taking a biologic for rheumatoid arthritis, psoriasis, or Crohn’s disease, the goal is to quiet your overactive immune system. But that same suppression makes you more vulnerable to infections-some serious, some preventable. The data doesn’t mince words: patients on biologics face a 2.1 times higher risk of being hospitalized for an infection compared to those on traditional treatments. That’s not a small bump. It’s a red flag that demands action.
Why Biologics Increase Infection Risk
Biologics aren’t like regular pills. They’re made from living cells and target specific parts of your immune system. TNF inhibitors like adalimumab and infliximab block a key inflammatory signal, but that same signal also helps your body fight off bacteria and viruses. Without it, your defenses weaken. The result? Respiratory infections-like pneumonia and bronchitis-make up nearly half of all serious infections in biologic users. Fungal infections like candidiasis rise with IL-17 inhibitors. And herpes zoster (shingles) becomes far more common with JAK inhibitors. Not all biologics carry the same risk. TNF blockers are the most scrutinized, responsible for about 68% of prescriptions. But newer agents like ustekinumab (an IL-12/23 inhibitor) show significantly lower infection rates. Certolizumab pegol, because of its unique structure, has a 18% lower risk of respiratory infections than other TNF inhibitors. The takeaway? Your choice of drug matters. But even the safest biologic still needs careful management.Screening Before You Start: The Non-Negotiable Steps
Starting a biologic without screening is like driving without checking your brakes. Three tests are mandatory before your first dose:- HBsAg - checks for active hepatitis B
- HBcAb - detects past exposure to hepatitis B
- HBsAb - confirms immunity from vaccination or prior infection
Vaccinations: Timing Is Everything
You can’t get vaccinated while on a biologic and expect full protection. Your immune system is too suppressed. So you have to do it before you start.- Live vaccines (MMR, varicella, nasal flu) - must be given at least 4 weeks before your first biologic dose
- Inactivated vaccines (flu shot, pneumococcal, hepatitis B, Shingrix) - give at least 2 weeks before
Who’s at Highest Risk?
Not everyone faces the same danger. Your risk spikes if:- You’re over 50 - each decade adds 37% more infection risk
- You’re on prednisone or another steroid at more than 10mg/day - that alone multiplies your risk by 2.3x
- You have diabetes, COPD, or chronic kidney disease - each raises your odds by 1.9 to 2.4 times
What Patients Are Really Experiencing
Real stories show the gap between guidelines and reality. One patient on MyTherapy wrote: “My pre-biologic workup at Mayo Clinic caught my latent TB. They treated me for 9 months. I’ve been on Humira for 3 years-zero infections.” That’s the ideal. Another on HealthUnlocked said: “My GI doctor started Stelara without checking my vaccines. Four months later, I got shingles.” That’s the reality for too many. A 2023 survey found that 63% of patients reported at least one screening or vaccination omission. The most common? Missing HBV core antibody testing and not checking VZV immunity. The good news? Patients who received a full CDC 12-point infection prevention checklist had a 78% rate of zero serious infections-compared to just 43% without education.
What You Need to Do Right Now
If you’re about to start a biologic-or already on one-here’s your action list:- Request full hepatitis B screening: HBsAg, HBcAb, HBsAb. If HBcAb is positive, demand HBV DNA testing.
- Review your vaccine record. If you’ve never had chickenpox or the varicella vaccine, get it now-before starting.
- Get Shingrix if you’re over 50, even if you’ve had shingles before.
- Get pneumococcal vaccines (PCV20 and PPSV23) if you haven’t already.
- Ask your doctor: “Am I on a high-risk biologic? Do I need prophylaxis?”
- Keep a personal health log: dates of vaccines, screening results, and any infections.
What’s Changing in 2025 and Beyond
The rules are tightening. The FDA now requires real-world evidence of infection risk reduction for any new biologic label expansion. The CDC’s updated BMBL 7th Edition, coming in October 2025, will include specific safety protocols for biologic users-like standardized PPE guidelines for healthcare workers handling these drugs. AI tools like the Cerner Biologics Safety Algorithm are now being used in major hospitals to predict individual infection risk using 87 clinical variables. And by 2026, Medicare will tie 15% of biologic payments to whether clinics documented proper screening and vaccination. The message is clear: safety isn’t optional. It’s the foundation.Frequently Asked Questions
Can I get the flu shot while on biologics?
Yes, but only if it’s the inactivated (shot) version, not the nasal spray. The flu shot is safe and recommended every year. However, your immune response might be weaker than someone not on biologics. That’s why getting it before you start treatment is ideal. If you’re already on a biologic, get it as soon as possible-don’t wait.
Do I need to stop my biologic if I get an infection?
Usually, yes. If you develop a serious infection-like pneumonia, sepsis, or tuberculosis-you’ll need to pause your biologic until you’re fully recovered. For minor infections like a cold or mild urinary tract infection, you might continue, but always check with your doctor. Never ignore fever, chills, or unexplained fatigue.
Is it safe to take biologics if I’ve had cancer?
It depends. If your cancer is in complete remission for at least 5 years and you’re not on chemotherapy, many biologics can be used cautiously. But TNF inhibitors carry a higher theoretical risk of cancer recurrence. Your rheumatologist or gastroenterologist will weigh your individual risk. Some newer agents, like IL-17 inhibitors, may be preferred in this group.
Why is hepatitis B screening so important?
Because hepatitis B can lie hidden in your liver for years. If you’re infected-even without symptoms-and start a biologic, the virus can suddenly reactivate. This isn’t rare: without treatment, 27.6% of people with past HBV exposure will have a dangerous reactivation. Testing for HBcAb and HBV DNA can catch this before it’s too late. It’s a simple blood test that prevents life-threatening liver damage.
What if I can’t get all my vaccines before starting?
If you’re already on a biologic and missed vaccines, don’t panic-but act fast. Inactivated vaccines can still be given, though they may not work as well. Live vaccines are off-limits once you’re on treatment. Talk to your doctor about checking your antibody levels. For hepatitis B, if your anti-HBs is below 10 mIU/mL, you may need a full booster series. For shingles, if you’re over 50 and never got Shingrix, get it even if you’re on a biologic-it’s still better than nothing.
