Auditing the efficacy of prophylactic measures against Covid-19 amongst Healthcare workers in India

To the editor,

We read with interest, the study published in this journal on February 12, 2021, by dos Santos et al. entitled: Recurrent COVID-19 including evidence of reinfection and enhanced severity in thirty Brazilian healthcare workers¹ that reported evidence of re-infection, and its association with a waning antibody response.

The increasing availability of effective vaccines represents a much-needed ray of hope. That said, the emergence of variants, global “second waves”, and vaccine supply-chain limitations underscore the continued need for vigilance regarding personal protection.

In this context, we believed that the results of an audit we conducted of the protective measures adopted by healthcare workers across India would be of interest.

The audit included healthcare workers involved in the care of covid-positive patients from March - October 2020; independent of underlying comorbidities; who had consistently adhered to a protocol comprising the use of personal protective equipment (PPE), patient proximity restrictions, sanitation of surroundings, and choice of pharmaco-prophylactic agent (400 mg of hydroxychloroquine weekly, daily arsenic alba, or none). The occurrence of swab-positive symptomatic disease was recorded as the endpoint. Participants also reported symptoms consistent with covid, despite being swab negative. This was considered separately, due to high false-negative RT-PCR rates.²

The study included a total of 834 healthcare workers including general practitioners (GPs), specialists, nurses, dentists, para-clinical support staff, and practitioners of traditional(alternative) medicine. The mean age was 44.8 ± 12.1 years. 498 had no comorbidities, 159 had hypertension, 129 were overweight, 92 were diabetic, 39 had pre-existing pulmonary diseases (asthma/COPD), 19 were active smokers, 9 had hypothyroidism, 8 had ischemic heart disease. 97 respondents had 2 or more coexistent comorbidities, with an overlap between diabetes mellitus, overweight and hypertension being the most prevalent.

56 respondents (6.71%) tested positive for covid-19; and further 56 developed symptoms consistent with covid-19 but were swab-negative. 11 of those who tested positive required non-invasive ventilatory assistance. None required invasive ventilatory support.

We assessed the risk attributable to each of the recorded parameters in developing disease.

Role/specialty

The proportional occurrence of covid-positivity amongst different specialties was compared (detailed in Table 1 ), using Internal Medicine and allied subspecialties as control, as this group constituted the largest cohort of respondents.

Table 1.

Quantifying the risk of contracting swab-positive disease based on field of practice:.

Sr. No.	Specialty	Proportion testing positive for covid-19 (%)	Relative Risk	95% Confidence Intervals	P value
1.	Surgery and Allied	7.3	1.72	0.74 – 4.00	0.20
2.	Radiology	0	0.47	0.02 – 7.77	0.60
3.	Paediatrics	6.5	1.53	0.36 – 6.42	0.58
4.	Paramedical support staff	6.7	1.58	0.22 – 11.24	0.64
5.	Nursing staff	8.3	1.97	0.28 – 13.82	0.68
6.	Non-clinical branches	0	0.47	0.02 – 7.77	0.60
7.	Interns	6.7	1.58	0.37 – 6.63	0.62
8.	Gynecology and obstetrics	7.5	1.78	0.61 – 5.23	0.28
9.	General Practitioners / Family Physicians	13.0	3.09	1.58 – 6.04	<0.001
10.	Dentists	0	0.82	0.51 – 13.06	0.88
11.	Anaesthesiology and critical care	10.9	2.57	0.97 – 6.82	0.056
12.	Alternative medicine practitioners	0	2.87	0.2 – 40.2	0.43
13.	Administrators	0	1.91	0.12 – 28.51	0.63
14.	Internal medicine and allied subspecialties (Control group)	4.2	–	–	–

General practitioners were identified as the greatest-at-risk sub-group (Relative risk[RR]:3.09, 95% Confidence Intervals[CI] – 1.58–6.04, p<0.001). The next highest-at-risk group was that of anaesthesiologists/intensivists.

Masks alone versus with face shields

Contrasting with previous reports³, the risk of developing illness did not increase significantly amongst workers who used only n95 masks versus those who used face shields additionally (RR 1.68, p = 0.24).

Physical distancing

547 respondents reported that they were able to maintain >1 m during patient interactions. The rate of symptomatic swab-negative disease was 7.1% with no distancing vs 5.6% with distancing (RR: 0.56, 95% CI: 0.34 – 0.93, p = 0.025).

There was no significant difference in terms of swab-positive disease (6.0% with distancing vs 8.0% without; p = 0.93).

Sanitization

645 participants reported maintaining strict sanitation of all workstations. The most used modalities were alcohol-based wipes (78.7%), hypochlorite solutions (56.7%), ordinary soap (54.7%), ultra-violet light (5.8%) and fumigation (0.2%). 532 workers used 2 or more modalities to achieve satisfactory levels of sanitization.

Swab-positive disease rates reduced from 9.6% without sanitization to 5.9% with strict sanitization (RR: 0.61, 95% CI: 0.35 – 1.05, p = 0.07). Swab-negative disease occurrence reduced from 8.5% without to 6.2% with strict sanitization (RR: 0.73, 95% CI: 0.41 – 1.27, p = 0.27).

Prophylactic pharmacotherapy

Participants were classified into 4 groups based on their choice of prophylactic pharmacotherapy: Controls (186 i.e., 22.3%, not using any medication), Hydroxychloroquine users (441, 52.9%) users of alternative medicine (51, 6.1%) and Combined HCQ + Alternative medicine (156, 18.7%).

Swab positive disease occurred in 4.3% of controls, 7.0% of HCQ users, 9.8% of alternative medicine users, 7.7% of combined users.

The relative risk (RR) for developing swab-positive disease was as follows: for HCQ use alone (RR: 1.63, p = 0.20), use of alternative medicine alone (RR: 2.27, p = 0.13) and for combined use of HCQ and alternative medicine (RR:1.8, p = 0.18).

These findings were stratified based on the number of covid patients seen by practitioners per day into 3 groups: those seeing <5/day, 5–10/day and >10/day. The increased risk was statistically significant for the use of “alternative” prophylaxis amongst practitioners who saw between 5 and 10 covid patients per day (RR: 16.72, 95% CI: 2.06–135.27, p = 0.008).

Exposure was also stratified based on the cumulative duration of exposure in a covid-replete setting as follows: <15 days, 15 days-1month, 1–3months and >3months. The risk of swab-positive disease increased statistically significantly in the subgroup of practitioners utilizing alternative medicine-based prophylaxis who were in such a setting for between 1 and 3 months (RR: 5.60, 95% CI: 1.48–21.14, p = 0.01).

When stratified to assess the effect of HCQ prophylaxis on preventing relatively severe disease manifestations (defined as any requirement of non-invasive ventilatory assistance[NIV]), no benefit was noted in this study population (RR for requiring NIV: 4.21, 95% CI: 0.26–67.02, p = 0.30).

The study found no benefit to the use of any pharmaco-prophylactic agent, both singly and in combination. Indeed, there was a tendency towards an increased risk.

Summarily, this study supports the continued use of standard protective measures including continued use of n-95 masks, maintenance of physical distancing>1 m from patients, when feasible, and advises against the use of pharmaco-prophylactic agents.