According to Gram Research analysis, COVID-19 caused a 33% drop in tuberculosis diagnoses in Northeast Iran from 2019 to 2020, with recovery lagging significantly behind. The study of 14,572 patients found a 10.3% TB positivity rate, with spring months showing the highest case numbers at 27.8% of annual diagnoses, possibly linked to vitamin D deficiency and seasonal social gatherings. Older adults (65+) and women represented over half of TB cases, highlighting the need for targeted screening during health crises.
When COVID-19 hit in 2020, hospitals in Northeast Iran saw a dramatic drop in tuberculosis diagnoses—down 33% compared to the previous year. Researchers studied nearly 15,000 patients tested for TB between 2017 and 2023 to understand how the pandemic disrupted disease detection. They found that older adults and women made up most TB cases, and that spring months showed more TB cases, possibly due to vitamin D deficiency after winter and social gatherings. The study highlights how pandemics can disrupt detection of other serious diseases and suggests hospitals need better plans to keep TB screening going during health crises.
Key Statistics
A cross-sectional analysis of 14,572 patients at a hospital in Northeast Iran found that COVID-19 caused a 33% decline in tuberculosis diagnoses from 2019 to 2020, with statistical confirmation of a structural break in March 2020.
Among 14,572 TB-suspected patients tested between 2017-2023, the overall positivity rate was 10.3% (1,494 cases), with spring months accounting for 27.8% of annual diagnoses, suggesting a seasonal transmission pattern.
In the Iranian hospital study, bronchoalveolar lavage testing identified the highest TB positivity rate at 54.7%, detecting 135 smear-negative cases that would have been missed by standard microscopy alone.
The 2026 cross-sectional study found that adults aged 65 and older represented 51.6% of TB cases, while females accounted for 51.7% of diagnoses, indicating demographic disparities in disease burden.
The Quick Take
- What they studied: How COVID-19 disrupted tuberculosis (TB) testing and diagnosis in a hospital in Northeast Iran, and whether TB cases followed seasonal patterns
- Who participated: 14,572 patients suspected of having TB who were tested at Qaem University Hospital in Mashhad, Iran between 2017 and 2023. About half were female, and more than half were age 65 or older
- Key finding: TB diagnoses dropped 33% from 2019 to 2020 when COVID-19 hit. The study also found that spring months had the most TB cases (27.8%), possibly linked to low vitamin D levels after winter
- What it means for you: If you live in an area affected by health crises, TB screening might be delayed. Older adults should be especially vigilant about getting tested for TB symptoms. The seasonal pattern suggests vitamin D and social gathering precautions in spring may help reduce transmission
The Research Details
Researchers looked back at medical records from 2017 to 2023 at one hospital in Iran to track TB testing patterns. They used three different testing methods: smear microscopy (looking at samples under a microscope), culture tests (growing the bacteria), and PCR (a genetic test). They compared how many people tested positive before, during, and after COVID-19 lockdowns. They also looked at whether certain groups—like older people or women—had different rates of TB. The study used statistical methods to identify exactly when the pandemic caused a sharp drop in diagnoses (March 2020) and whether TB cases followed seasonal patterns.
This research approach is important because it shows real-world impacts of pandemic disruptions on other diseases. By looking at actual hospital data over several years, researchers could see the exact moment when COVID-19 disrupted TB testing and track how long recovery took. Understanding these patterns helps hospitals prepare for future health crises and ensure TB screening doesn’t get abandoned when other diseases emerge
This study has some strengths: it used a large sample (nearly 15,000 patients), multiple testing methods, and statistical techniques to identify the exact timing of disruptions. However, it’s limited to one hospital in one region of Iran, so results may not apply everywhere. The study is observational (looking at what happened) rather than experimental, so it can identify patterns but not prove direct cause-and-effect. The demographic differences found were statistically significant but relatively small in practical terms
What the Results Show
Out of 14,572 patients tested for TB, 1,494 tested positive—a 10.3% positivity rate. When COVID-19 hit in March 2020, TB diagnoses dropped sharply by 33% compared to 2019. This decline was confirmed by statistical analysis showing a clear structural break in the data. Importantly, inpatient services (hospital admissions) recovered faster than outpatient services (clinic visits), suggesting that people with severe TB were still being caught but milder cases were being missed. The pandemic’s impact lasted throughout the study period, indicating that TB screening never fully recovered to pre-pandemic levels during the timeframe studied.
The study found important demographic patterns: 51.7% of TB cases were female, and 51.6% were age 65 or older. A special test called bronchoalveolar lavage (taking samples from deep in the lungs) had the highest success rate at 54.7% positivity. This test identified 135 cases that would have been missed by standard smear microscopy. Spring months (March-May) showed the highest TB cases at 27.8% of annual cases, suggesting a seasonal pattern. Researchers hypothesized this spring surge relates to vitamin D deficiency after winter months and increased social contact during Nowruz (Persian New Year celebrations)
This study adds to growing evidence that COVID-19 disrupted diagnosis of non-COVID diseases worldwide. Previous research showed similar patterns in other countries—TB diagnosis dropped globally during 2020-2021. The seasonal pattern found here (spring peaks) aligns with some previous TB research suggesting vitamin D plays a role in TB transmission. However, the specific 33% decline in this Iranian hospital is consistent with reports from other regions, confirming that pandemic disruptions to TB services were widespread, not isolated
The study only looked at one hospital in one region of Iran, so findings may not apply to other areas or countries with different healthcare systems. It’s observational data, meaning researchers couldn’t control variables or prove that COVID-19 directly caused the decline (though the timing strongly suggests it). The study couldn’t determine why spring had more cases—the vitamin D hypothesis is reasonable but not proven. The demographic differences found were statistically significant but small in practical effect size. Finally, the study ends in 2023, so it doesn’t show whether TB services have fully recovered since then
The Bottom Line
Healthcare systems should develop pandemic-resilient TB screening protocols that continue during health crises (high confidence). Hospitals should prioritize geriatric TB screening, especially for adults over 65 (moderate-to-high confidence). Communities should consider vitamin D supplementation programs in winter months and respiratory screening during spring gatherings (moderate confidence, based on seasonal pattern hypothesis). Policymakers should integrate TB screening into routine respiratory disease protocols rather than treating it as a separate service (moderate-to-high confidence)
Older adults (65+) should be especially aware of TB symptoms and seek testing if they have persistent cough or other respiratory symptoms. Healthcare workers and hospital administrators in regions with TB should use this research to strengthen pandemic preparedness. People living in areas with seasonal health disruptions should be vigilant about TB screening in spring. Public health officials should consider this when planning disease surveillance systems. People with risk factors for TB (immunocompromised individuals, those in close contact with TB patients) should ensure they’re tested regularly regardless of pandemic status
TB symptoms typically develop slowly over weeks to months, so seasonal peaks may reflect infections acquired in previous months. If healthcare systems implement the recommended screening improvements, faster diagnosis could occur within months. However, rebuilding TB surveillance systems disrupted by pandemics typically takes 6-12 months. Individuals who get tested and treated can see improvement in symptoms within 2-4 weeks of starting TB medication, though full treatment takes 6 months
Frequently Asked Questions
Did COVID-19 really stop tuberculosis testing in hospitals?
Yes, significantly. A 2026 study of 14,572 patients in Iran found TB diagnoses dropped 33% from 2019 to 2020 when COVID-19 hit. Outpatient clinic testing was especially disrupted, though hospital admissions for severe TB continued at higher rates.
Why do more TB cases happen in spring?
The research found 27.8% of annual TB cases occurred in spring (March-May). Researchers hypothesize this relates to vitamin D deficiency after winter months and increased social contact during spring celebrations, though this wasn’t directly proven in the study.
Who is most likely to get tuberculosis according to this research?
Adults over 65 represented 51.6% of TB cases, and women accounted for 51.7% of diagnoses in this Iranian hospital study. Older adults should be prioritized for TB screening, especially during health system disruptions.
What’s the best test to diagnose tuberculosis?
The study found bronchoalveolar lavage (taking samples from deep in the lungs) had the highest success rate at 54.7% positivity. However, standard smear microscopy and culture tests remain important because they’re more practical for routine screening.
How long does it take to recover from tuberculosis?
The study didn’t address treatment duration, but standard TB treatment typically takes 6 months with medication. Symptoms may improve within 2-4 weeks of starting treatment, though patients remain contagious initially and need to follow medical guidance.
Want to Apply This Research?
- Track respiratory symptoms (persistent cough, night sweats, fever) weekly, noting the season and any recent social gatherings. Users can log symptom severity on a 1-10 scale and note when they received TB screening tests
- Set reminders for TB screening during spring months (March-May) if you’re in a high-risk group. Log vitamin D supplementation during winter months (November-February) to track whether it correlates with fewer respiratory symptoms
- Create a seasonal health calendar marking high-risk periods (spring for TB transmission, winter for vitamin D deficiency). Track TB test results annually and note any pandemic-related healthcare disruptions in your area. Monitor respiratory symptoms year-round but pay special attention during spring months
This research describes patterns observed in one Iranian hospital and may not apply to all regions or healthcare systems. The study is observational and cannot prove direct cause-and-effect relationships. If you have symptoms of tuberculosis (persistent cough lasting more than 3 weeks, night sweats, fever, or weight loss), consult a healthcare provider for proper testing and diagnosis. Do not self-diagnose or delay medical care based on this research. Tuberculosis is a serious, treatable infection that requires professional medical evaluation and treatment. This article is for informational purposes and should not replace medical advice from qualified healthcare professionals.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.