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Year : 2021  |  Volume : 9  |  Issue : 2  |  Page : 131

Air droplet versus airborne transmission – Essential concepts for understanding COVID-19 infection control

1 Department of Community and Family Medicine, AIIMS, Mangalagiri, Guntur, Andhra Pradesh, India
2 Department of ENT and Head and Neck Surg, AIIMS, Mangalagiri, Guntur, Andhra Pradesh, India

Date of Submission06-Aug-2021
Date of Decision04-Oct-2021
Date of Acceptance07-Sep-2021
Date of Web Publication30-Nov-2021

Correspondence Address:
Satvinder Singh Bakshi
Department of ENT and Head and Neck Surgery, AIIMS, Mangalagiri, Guntur - 522 503, Andhra Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/dmr.dmr_25_21

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How to cite this article:
Kalidoss VK, Bakshi SS. Air droplet versus airborne transmission – Essential concepts for understanding COVID-19 infection control. Dent Med Res 2021;9:131

How to cite this URL:
Kalidoss VK, Bakshi SS. Air droplet versus airborne transmission – Essential concepts for understanding COVID-19 infection control. Dent Med Res [serial online] 2021 [cited 2023 Jan 30];9:131. Available from: https://www.dmrjournal.org/text.asp?2021/9/2/131/331396

Dear Editor,

Air droplet transmission occurs through large infected droplets (>5 μm) during coughing, sneezing, talking, or singing by infected person to the person nearby (within 1 m). Infections such as Neisseria meningitidis, Streptococcus, and Respiratory syncytial virus transmit through air droplets. The transmission can occur either directly from person to person in close contact or indirectly through contaminated objects or surface (fomite transmission). In March 2020, the World Health Organization (WHO) suggested current coronavirus disease - 2019 (COVID-19) pandemic is primarily transmitted via respiratory droplets. In this context, they recommended preventive and control measures such as physical barriers, physical distancing, use of masks within droplet distance (within 1 m), respiratory etiquette, and wearing high-grade protection such as respirator, N95 or FFP2, or FFP3 masks during aerosol-generating procedures (AGPs).[1]

Airborne infections are transmitted through droplet nuclei <5 μm in diameter and can remain in the air for a longer period of time and therefore can be transmitted to others over distances >1 m. Infections such as tuberculosis, measles, and chickenpox are transmitted through airborne route. Prevention and control measures for airborne transmission require measures to avoid inhalation of infectious aerosols, including natural ventilation, air filtration (HEPA-filter if room air is re-circulated), reducing crowding and time spent indoors, use of masks whenever indoors, attention to mask quality and fit, and higher-grade protection (N95 or FFP2 or FFP3) for health-care staff and frontline workers.[2]

In the context of the current pandemic, WHO in July 2020 started evaluating the possibility of airborne transmission of SARS-CoV-2 in the absence of AGPs, particularly in indoor settings with poor ventilation.[3] Greenhalgh et al. in their manuscript enumerated many possible explanations for airborne transmission of SARS-CoV-2. This discovery has two important implications: first, crowded and poorly ventilated places have high risk of transmission and second, we may need to use N95 or equivalent respirators even in the absence of AGP.[4] The WHO Environment and Engineering Control Expert Advisory Panel for COVID-19 on the environment and engineering controls has given multiple recommendations regarding ventilation in various settings for control of the infection.[5] These recommendations should be incorporated by governments worldwide in their fight against the coronavirus.

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Conflicts of interest

There are no conflicts of interest.

  References Top

World Health Organization. Modes of Transmission of Virus Causing COVID-19: Implications for IPC Precaution Recommendations. 2020. Available from: https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations. [Last accessed on 2021 May 15].  Back to cited text no. 1
Ather B, Mirza TM, Edemekong PF. Airborne Precautions. StatPearls. Treasure Island (FL): StatPearls Publishing; 2021.  Back to cited text no. 2
World Health Organization. Transmission of SARS-CoV-2: Implications for Infection Prevention Precautions. 2020. Available from: https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions. [Last accessed on 2021 May 15].  Back to cited text no. 3
Greenhalgh T, Jimenez JL, Prather KA, Tufekci Z, Fisman D, Schooley R. Ten scientific reasons in support of airborne transmission of SARS-CoV-2. Lancet 2021;397:1603-5.  Back to cited text no. 4
World Health Organization. Roadmap to Improve and Ensure Good Indoor Ventilation in the Context of COVID-19. Geneva, Switzerland; 2021. Available from: https://www.who.int/publications/i/item/9789240021280. [Last accessed on 2021 May 16].  Back to cited text no. 5


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