When you're managing an autoimmune disease like rheumatoid arthritis, psoriasis, or Crohnâs disease, biologics can change your life. These targeted drugs-monoclonal antibodies and fusion proteins-quiet the overactive immune system thatâs attacking your own body. But thereâs a hidden cost: biologics increase your risk of serious infections. Not a little bit. A lot. Studies show patients on these drugs are more than twice as likely to end up in the hospital because of an infection compared to those on older medications. The good news? This risk isnât random. Itâs predictable. And itâs manageable-if you know exactly what to do.
Why Biologics Raise Infection Risk
Biologics donât just calm down your immune system. They turn off specific parts of it. TNF inhibitors like adalimumab and infliximab block a key protein called tumor necrosis factor, which your body uses to fight off bacteria and fungi. Thatâs why they work so well for inflammation. But it also means your body canât respond as quickly when a new infection shows up. The result? Tuberculosis can wake up from hiding. Fungal infections like histoplasmosis can spread unchecked. Even common viruses like shingles become more dangerous. Not all biologics carry the same risk. TNF blockers are the most notorious. Data from 28,942 patients across 47 trials shows they raise serious infection rates by 1.6 to 1.9 times compared to newer agents like ustekinumab or secukinumab. Why? Because they hit a broader target. IL-17 inhibitors, for example, leave more of your immune system intact, but they come with their own trade-off: higher rates of candidiasis. JAK inhibitors like tofacitinib spike herpes zoster risk by 33% compared to traditional biologics. Knowing which drug youâre on isnât just about effectiveness-itâs about survival.Screening: The Non-Negotiable First Step
Before you even get your first biologic injection, you need three blood tests. Not one. Not two. Three. Hepatitis B screening is mandatory. You need to check for HBsAg (surface antigen), HBsAb (surface antibody), and HBcAb (core antibody). Why? Because 4.3% of people with autoimmune diseases carry hidden hepatitis B. If you start a TNF inhibitor without knowing this, your chance of a deadly reactivation jumps to 27.6%. Thatâs not a risk you take lightly. If HBcAb is positive, even if HBsAg is negative, you still need a DNA test to rule out occult infection. The American Association for the Study of Liver Diseases says so. The CDC says so. And if you skip this? Youâre gambling with your liver. Tuberculosis screening is next. Most clinics use interferon-gamma release assays (IGRAs) like QuantiFERON. Theyâre 98% specific. But hereâs the catch: in low-prevalence areas, up to 12.7% of patients test positive even if theyâve never had TB. That doesnât mean theyâre infected-it means the test is picking up past exposure. The real issue? Not every doctor knows how to interpret this. Some start biologics anyway. Others delay treatment for months. The solution? Treat latent TB with nine months of isoniazid before starting biologics. Itâs not optional. Itâs the standard.Vaccination: Timing Is Everything
Vaccines are your first line of defense. But they only work if given at the right time. Live vaccines-like MMR and varicella-must be given at least four weeks before your first biologic dose. Why? Because your immune system needs time to build a response before the drug shuts down the reaction. If you get the chickenpox shot after starting adalimumab? You could end up with a full-blown case of chickenpox. Itâs happened. Inactivated vaccines-flu, pneumococcal, tetanus-are safer but still need lead time. Get them at least two weeks before biologics. The CDC recommends checking antibody levels after hepatitis B vaccination. You need anti-HBs levels above 10 mIU/mL to be protected. If youâre below that? You get another shot. And another. Donât assume one shot is enough. The same goes for varicella: IgG levels must be at least 140 mIU/mL. If not, youâre still vulnerable. And yes-Shingrix is critical. Even if you had chickenpox as a kid, your immunity fades. The CDC recommends two doses of Shingrix for everyone over 50 on biologics. But hereâs the problem: 37% of patients never get screened for VZV immunity before starting treatment. Thatâs why so many end up with shingles within months.
Whoâs at Highest Risk?
Not everyone on biologics gets sick. But some are far more likely to. Age matters. Every decade over 50 increases your infection risk by 37%. Diabetes? That adds nearly a two-fold increase. Chronic kidney disease? Risk jumps 2.15 times. COPD? 2.41 times. And if youâre on prednisone at 10 mg or more per day? Youâre adding 2.3 times more risk on top of the biologic. Thatâs a dangerous combo. Many patients donât realize their steroid dose is part of the problem. Reducing steroids-even by half-can cut infection rates dramatically. Geography plays a role too. In rural areas, only 28% of patients complete all required screenings. Thatâs not because theyâre careless. Itâs because their doctors donât have the tools. Labs donât offer HBcAb testing. Vaccines arenât stocked. Telehealth platforms are changing that, but slowly. The 2025 National Biologics Safety Action Plan is pushing for remote screening kits and digital record systems to fix this gap.Real Stories, Real Mistakes
One patient from Texas, age 62, started Humira for psoriasis. Her doctor skipped the hepatitis B test. Three months later, she was in the hospital with acute liver failure. She didnât know sheâd been exposed as a child. She survived-but barely. Another, from Minnesota, got Stelara for Crohnâs without ever getting Shingrix. Four months later, he had a severe shingles outbreak that left nerve damage in his arm. His GI specialist didnât know the vaccine timeline. Heâs now on long-term pain meds. These arenât rare. A 2023 survey of over 1,200 patients found 63% had at least one screening step missed. The most common? HBV core antibody testing (41%) and varicella immunity check (37%).
What You Need to Do Now
If youâre about to start a biologic, hereâs your checklist:- Get tested for HBsAg, HBsAb, and HBcAb-no exceptions.
- Do an IGRA test for TB. If positive, start treatment before biologics.
- Check your varicella immunity with IgG titer. If below 140 mIU/mL, get two doses of Shingrix.
- Get flu shot, pneumococcal vaccine (PCV20 or PPSV23), and tetanus booster-all at least two weeks before your first dose.
- Stop live vaccines (MMR, varicella) if you havenât had them. Get them now, if eligible, at least four weeks out.
- Ask your doctor to review your steroid use. Can it be lowered?
- Request a copy of your screening results. Keep them in your personal health file.
The Future Is Data-Driven
New tools are emerging. AI models like the Cerner Biologics Safety Algorithm now analyze 87 data points-age, lab values, medication history, geography-to give you a personalized infection risk score. In 2023, it was validated in a JAMA study with 87% accuracy. Hospitals are starting to use it. Insurance companies are pushing for it. By 2026, CMS will tie 15% of biologic payments to documented safety steps. That means clinics that skip screenings will lose money. And patients? Theyâll finally get the protection they deserve.Final Thought
Biologics arenât dangerous. Theyâre powerful. And like any powerful tool, they need rules. Skipping a blood test. Delaying a vaccine. Ignoring your steroid dose. These arenât small oversights. Theyâre avoidable mistakes with life-altering consequences. Youâre not just taking a drug. Youâre entering a safety system. And that system only works if youâre part of it. Donât wait for your doctor to bring it up. Ask. Push. Demand. Your immune system will thank you.Do all biologics carry the same infection risk?
No. TNF inhibitors like adalimumab and infliximab have the highest infection risk, increasing hospitalization rates by 1.6 to 1.9 times compared to non-TNF biologics. IL-17 inhibitors (e.g., secukinumab) and IL-12/23 inhibitors (e.g., ustekinumab) have lower overall infection rates, though they may increase risk of specific infections like candidiasis. JAK inhibitors like tofacitinib carry a higher risk of shingles. The choice of drug should be based on your personal risk profile, not just effectiveness.
Can I get vaccinated after starting a biologic?
Live vaccines (MMR, varicella, nasal flu) should never be given after starting biologics-they can cause serious infection. Inactivated vaccines (flu shot, pneumococcal, tetanus) can be given after starting, but they may not work as well because your immune system is suppressed. The best practice is to complete all vaccines at least two weeks before your first biologic dose. If youâve already started, check with your doctor about antibody levels to see if youâre protected.
What if I test positive for latent TB but donât want to take antibiotics?
Skipping treatment for latent TB before starting a biologic is dangerous. Without treatment, the risk of active TB reactivation is over 25% in patients on TNF inhibitors. The standard treatment-nine months of isoniazid-is safe for most people. Side effects like liver inflammation are rare and monitored. If youâre concerned, ask about rifampin-based regimens, which last only four months. But donât refuse treatment. The risk of TB spreading to your lungs, bones, or brain is far worse than the side effects of the medication.
Why is hepatitis B screening so important before biologics?
Hepatitis B can lie dormant in your liver for years. When you take a TNF inhibitor, it can wake up the virus and cause sudden, severe liver damage-or even death. Studies show that without screening and prophylaxis, 27.6% of patients with hidden HBV will reactivate. Screening with HBsAg, HBsAb, and HBcAb catches this. If HBcAb is positive, even if HBsAg is negative, you still need HBV DNA testing because 8.7% of these patients have occult infection. Treatment with antivirals like entecavir before starting biologics reduces reactivation risk to under 1%.
I had chickenpox as a kid. Do I still need the Shingrix vaccine?
Yes. Even if you had chickenpox, your immunity fades over time. The CDC recommends two doses of Shingrix for all adults over 50 on biologics, regardless of past infection. Shingles risk increases with age and immune suppression. Studies show patients on biologics are 3 to 5 times more likely to get shingles than the general population. Skipping Shingrix is one of the most common reasons patients develop shingles within months of starting treatment. Donât assume past infection = lifelong protection.
How do I know if my doctor is following the right guidelines?
Ask for a copy of your pre-biologic screening checklist. It should include: HBV panel (HBsAg, HBsAb, HBcAb), IGRA or PPD for TB, varicella IgG titer, pneumococcal and flu vaccine records, and documentation of steroid use. If any of these are missing, ask why. The American College of Rheumatology and CDC guidelines are clear. If your doctor doesnât mention them, they may not be following current standards. You can also check the CDCâs Safe Labs Portal for the official 17-item checklist. Bring it with you to your appointment.
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