Coronavirus Disease 2019 (COVID-19) is a new and highly contagious respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), which presented a risk of infection from human to human. The current outbreak of COVID-19 has caused a global pandemic. In India, from January 2020 to October 2022 there have been 6.27 billion covid positive cases been confirmed, as detected by WHO. A total of 12.8 billion vaccines have been administered [1].

Frontline workers had to suffer both physical and mental health issues while taking care of COVID-19 patients, due to poor preparation for the unpredictable pandemic. They have been working without proper preparation, training or standardized guidelines. Thus, increasing the burden of contracting infection among the health care workers [3].

Pathophysiological events of COVID-19 involve lungs majorly, which induces diffuse alveolar epithelium destruction, hyaline membrane formation, capillary damage and bleeding, alveolar septal fibrous proliferation, and pulmonary consolidation. Extensive alveolar and epithelial injury mains to secondary fibroproliferation, this remodeling leads to lung fibrosis or pulmonary hypertension [3].

COVID 19 affects multiple organ systems. It is reported that approximately 30% of people with SARS or Middle East respiratory syndrome had persisting lung abnormalities after their acute illness [3]. Respiratory decline has been seen in patients on long term ventilation, diffuse lung involvement, and elderly [4].

This persistent change in lung function implies a structural lung change, which can be detected on CT of the chest. It is well known that interstitial pneumonia represents the most common cause of hospitalization for COVID-19, which was complicated by acute distress respiratory syndrome, refractory respiratory failure and death [5].

COVID-19 survivors are reporting residual abnormalities post discharge. The knowledge about COVID-19, including clinical manifestations, pathogenesis, even treatment came from research and observation during the acute infection period. Limited information is available about post discharge stage of recovery or the lingering effects of the virus on pulmonary function and inflammation [3].

Hence, this study was undertaken to provide data on the respiratory changes among the health cares workers post discharge. This result might help in emphasizing the need to identify and manage lung function abnormality vigorously in acute phase, which could reduce the long term abnormality in lung function.

This is a prospective cohort study was carried out over a period of 9 months to analyze the post covid lung function in healthcare workers of M S Ramaiah institute of medical sciences and research center. This study was conducted after assessment and approval from the Institutional Ethics Committee. Patient’s demographics, clinical and drug data, 6 minute walk test, casual drug details, outcomes and relevant investigation details were collected.

Descriptive Statistics of altered lung function was analysed and summarized in terms of percentage. The mean change in FEV1, FVC, FEV1/FVC was summarized in terms of mean with standard deviation. Paired t test was used to compare FEV, FVC and ratio of the two between baseline and after 3 months. Chi square test was used to compare the proportion of altered lung function between severity of HRCT chest score, difference of age, comorbidities. Level of significance fixed at p< 0.05.

Mean age of the study population was 43.44±13.91 years and 50% of the people were male. Most of the patients had co-morbidities like diabetes (17), hypertension (15), hypothyroidism (7) and bronchial asthma (7). Majority of the patients were treated at home and majority of the hospitalized patients received IV remdesivir and IV steroids. Mean CTSS score was 6.09±4.97. Severity scoring had majority of the patients in mild (45.88%) category followed by moderate (29.16%) and severe (25%). Health care workers presented with various symptoms, majority had fever (28.29%) followed by cough (19.55), breathlessness (10.02%), weakness (7.9%) and myalgia (5.3%).

When the groups were stratified into different groups based on severity. There were significant number of males in all the groups. CT score was significantly high in moderate (10.83±2.42) and severe (9±4.58) cases compared to mild cases (1.84±1.59). Use of intravenous remdesivir and steroids were high in moderate and sever cases compared to mild. Saturation was significantly reduced (90%) in severe cases compared to mild and moderate, though difference between mild and moderate was not significant.

The mean 6MWD increased significantly, from 368±18.61m at baseline to 403±11.79m at 12weeks (p value <0.001).  Spirometry was completed in all patients at baseline and at 12 weeks. At baseline spirometry showed abnormality in majority of the patients (54.16%). Even though most patients were free of respiratory symptoms at follow-up, lung function abnormality was observed in 43patients (44.7%). There was significant improvement in FEV1, PEF and FEV25-75% at follow-up from baseline.

Table 1: Baseline characteristics of covid positive patients at the time of diagnosis.

Descriptive statistics percentages

Figure 1: symptoms of covid positive healthcare workers at the time of diagnosis.

Table 2: shows the baseline characteristics of covid positive patients at baseline based on the severity of the disease.

Data analysed by repeated measures ANOVA (intra-group comparison), * p < 0.05 is considered statistically significant. Post hoc analysis using Tukey HSD test showed p < 0.05 between each visit is statistically significant for CT score and SPO2 (except between moderate and mild).

Table 3: pulmonary function variability at baseline and after 12weeks among patients with covid positive health care workers.

Data analysed by paired t-test and chi-square (intergroup comparison), * p <0.05 is considered statistically significant.

Health care workers were affected both physically and emotionally due to limited period of preparedness for the rapid increase in cases due to COVID-19 infection [6]. Presence of different variant strains of COVID-19 has emphasised the need for more data on clinical characteristics and management of disease. Our study emphasised to study the respiratory function in a cohort of healthcare workers that have tested positive, and have presented with continued respiratory symptoms.

Fever, cough, breathlessness and weakness were the most common presenting symptoms in our study. Fever and could be attributed to the infection and inflammation of the lungs. Breathlessness is due to decrease in respiratory muscle strength. Systemic use of corticosteroids might cause steroid myopathy leading to long term muscle weakness [4].

Males, High CT score, intravenous remdesivir, intravenous steroids and low SPO2 were the few factors associated with severe cases. Given the relatively well preserved lung function in the majority of the survivors, the functional limitation was observed in 21.8% of health care workers. Though co-morbidities had statistical significance among the different severity, majority of the chronic lung disease were seen in severe cases.

In present study 6MWT showed 12.5% improvement from baseline to 12weeks, with statistically significant increase in 6MWD. A study by Daher et al, reported no patients significantly desaturated during a 6MWT after 60days [2]. Fuglebjerg et al, demonstrated significant desaturation (SpO2 < 90%) on exertion during 6MWT at discharge [3]. This difference in incidence in desaturation could be due to change in severity of disease in the study population.

We found lung function abnormality at 12weeks was high as 44.7% among the health care workers. A possible explanation for the difference is the time of assessment. A study conducted by Zhao et al, reported a 16% prevalence at 3 months post discharge [7]. A study by Frija-Masson J et al, prevalence was 44% during the first month post-infection [3].

In the current study, we observed that was statistically significant improvement in ventilatory defects like FEV1%, FEV1/FVC, PEF and FEV (25-75%) from baseline to 12 weeks. A study conducted by Xiaoneng Mo et al, significant improvement in DLCO was observed, though parameters like FEV1, FVC, FEV1/FVC among the survivors showed no difference. This could be because baseline PFT was not done in this study [8]. In addition to acute lung injury, neuromuscular weakness could also lead to decreased lung function.

A study done by Huang et al, showed that 10.5% had obstructive disease pattern [4]. In our study, 33.33% had restrictive lung disease and 29.16% had obstructive lung disease. A confounding factor for obstructive pattern in our study was presence of chronic lung disease among 8 patients.

There are several limitations to this study. Small sample size. The main limitation of the present study is that, it was conducted in one hospital and hence results cannot be generalized. The study had small sample size and 12weeks follow-up data, selection bias might affect statistical outcome. Hence, longer follow-up on COVID-19 patients should be made to observe the characteristic and change tendency of lung function and exercise tolerance.

In conclusion, the present provided data about the respiratory function and its changes at 12weeks in a cohort of healthcare workers that have tested positive, and have presented with continued respiratory symptoms. This data might help in improving therapeutic outcomes in COVID-19 positive health care workers.

1. Who coronavirus (COVID-19). World health organization.
2. Daher A, Balfanz P, Cornelissen C, Muller A, Bergs I, Marx N, et al. Follow up of patients with severe coronavirus disease 2019 (COVID-19): pulmonary and extrapulmonary disease sequelae. Respir Med. 2020, 174.
3. Fuglebjerg NJU, Jensen TO, Hoyer N, Ryrso CK, Lindegaard B, Harboe ZB. Silent hypoxia in patients with SARS CoV-2 infection before hospital discharge. Int J Infect Dis. 2020, 99: 100-101.
4. Huang Y, Tan C, Wu J, Chen M, Wang Z, Luo L, et al. Impact of coronavirus disease 2019 on pulmonary function in early convalescence phase. Respir Res. 2020; 21: 163.
5. Gentile F, Aimo A, Forfori F, Clemente A, Cademartiri F, Emdin M, et al. COVID-19 and risk of pulmonary fibrosis: the importance of planning ahead. Eur J Prev Cardiol. 2020; 27: 1442-1446.
6. Koontalay A, Suksatan W, Prabsango K, Sadang JM. Health care workers’ Burdens during the COVID-19 Pandemic: A Qualitative Systemic Review. J MultidiscipHealthc.2021; 14: 3015-3025.
7. Zhao Y, Shang Y, Song W, Li Q, Xie H, Xu Q, et al. Follow-up study of the pulmonary function and related physiological characteristics of COVID-19 survivors three months after recovery. EClinical Medicine. 2020;100463
8. Mo X, Jian W, Su Z, Chen M, Peng H, Peng P, et al. Abnormal pulmonary function in COVID-19 patients at time of hospital discharge. Eur Respir J. 2020; 55: 2001217.