A Fresh Air Look at Ventilation

Environmental factors contribute to the spread of microorganisms causing diseases. Sunlight can kill viruses in minutes, while increased air pollution could be one of the risk factors of more severe outcomes. Humidity is also thought to be important. A team of scientists from Northeast US analyzed COVID-19 cases from 2669 counties and found that cold and dry weather and low levels of ultraviolet radiation are moderately associated with increased SARS-CoV-2 transmissibility, with humidity playing the largest role. 17.5% of the virus’ reproductive number was attributable to meteorological factors, with temperature accounted for 3.73%, humidity accounted for 9.35%, and UV radiation for 4.44%. This is in line with earlier findings about SARS-CoV-2 being less stable at higher humidity and warmer temperatures in human nasal mucus and sputum. Like in previous environmental studies, however, these fractions were not the same everywhere and were higher in northern counties. 

20 years ago, American scientists Wells and Riley developed a model of the airborne transmission of infectious diseases such as tuberculosis and measles. A novel modified version of this model was used to estimate the impact of relative humidity on the removal of respiratory droplets containing infectious virus particles. The results showed that this impact depended on the ventilation rate and the size range of virus-laden droplets.  It was concluded that increasing the ventilation rate is more beneficial, while installing and running humidifiers may not be an efficient solution to reduce the risk of COVID-19 disease in indoor spaces. 

A popular metric for airflow is Air Changes per Hour (ACH, also called Air Change Rate).  It tells how many times the air within a space can be replaced with fresh air each hour. Increasing the ventilation rate from 0.5 ACH to 6 ACH was predicted to decrease the infection risk by half. Studies of US houses and apartments found typical ACH values between 0.5 and 2.0 (with open windows). 4.0 ACH is the minimum air exchange rate acceptable for commercial buildings, but 1.5 ACH is the reality for most schools. Opening a car window raises ACH to 6.  Natural ventilation combined with novel technologies could help to increase fresh air intake with minimal energy cost.

Virus clouds can, indeed, be dispersed with some fresh, clean air. But fresh air isn’t going to stop the spread of microorganisms in high-density crowds. Effective ventilation is only one of basic infection control strategies along with hand/environmental hygiene, social distancing, case surveillance and other evidence-based measures. 

REFERENCES

Aganovic A, Bi Y, Cao G, Drangsholt F, Kurnitski J, Wargocki P. Estimating the impact of indoor relative humidity on SARS-CoV-2 airborne transmission risk using a new modification of the Wells-Riley model. Building and environment. 2021 Aug 23:108278.

Ma Y, Pei S, Shaman J, Dubrow R, Chen K. Role of meteorological factors in the transmission of SARS-CoV-2 in the United States. Nature Communications. 2021 Jun 14;12(1):1-9.

Anaphylaxis to COVID-19 vaccinies

Anaphylaxis  - severe, potentially life-threatening allergic reaction - can occur within seconds or minutes of exposure to allergens. Multiple cases of anaphylaxis have been described for COVID-19 vaccines. 

For the Pfizer/BioNTech vaccine, twenty-one anaphylaxis cases (a rate of 11.1 per million doses administered, later updated as 4.7/million from 28-million-datapoints), were documented in the US after receipt of the first dose of Pfizer-BioNTech COVID-19 vaccine during December 14–23, 2020. 17 of those had a documented history of allergies or allergic reactions, seven of whom had a history of anaphylaxis. 71% of them occurred within 15 min following the first dose of BioNTech vaccine. 

Anaphylactic shock to Pfizer vaccine happened in those with history of anaphylaxis to other vaccines (rabies and influenza A(H1N1) vaccine), drugs (prochlorperazine, antibiotics, sulfa drugs), venom (jellyfish sting) or nuts. Out of 21, 4 were allergic to sulfa drugs, 2 were allergic to nuts.

Moderna COVID-19 vaccine caused much fewer anaphylactic episodes (2.5 anaphylaxis cases per million doses administered for 27 million datapoints), but there were similarities with Pfizer cases. Out of 10 cases described in MMWR, 4 had Penicillin allergy (like 1 Pfizer case). Also, in common were allergies to sulfa drugs and azithromycin.   A Kansas woman who died 2nd day after experiencing anaphylactic reaction to her first Moderna shot, previously had an allergic reaction to Albuterol, a drug used to treat wheezing and shortness of breath.

The Pfizer-BioNTech vaccine contains lipid nanoparticles one of which is “pegylated” (Polyethylene glycol, molecular weight 2000 Da, abbreviated to PEG2000). The Moderna mRNA vaccine also includes a different pegylated lipid (also a PEG2000). Polyethylene glycols, also known as macrogols, could be causing serious allergic reactions ins some people.

One of the culprits of anaphylaxis in Astrazeneca could be polysorbate 80, used in the formulation of protein-based biopharmaceuticals, cosmetics, skin-care products, chewing gum and foods (ice creams and puddings). 41 reports of possible anaphylaxis were seen among around 5 million vaccinations in the United Kingdom. Four cases of people potentially experiencing anaphylactic reactions within 30 minutes of receiving the AstraZeneca vaccine have been reported in Queensland and one case with fatal outcome happened in Georgia. 

Polysorbate 80 is also an ingredient in Johnson and Johnson vaccine. For this vaccine, no cases of anaphylaxis were reported in ~22,000 participants of phase 3 clinical trial who received it. Five patients reported developing hives within a week. There was one case of what was considered severe “a hypersensitivity reaction,” but it was reportedly not related to anaphylaxis. Last month, however, one individual in South Africa developed anaphylaxis. No details have been published yet. 

According to the CDC, polysorbate 80 is an inactive ingredient in many viral vector vaccines for influenza (Fluarid, Fluax, etc), rotavirus, shingles, Hepatitis A, Hepatitis B, HPV, and meningococcus. Polysorbate 80 is also an ingredient in COVID-19 Sputnik V vaccine from Gamaleya Research Institute.

REFERENCES

Turner PJ, Ansotegui IJ, Campbell DE, Cardona V, Ebisawa M, Yehia EG, Fineman S, Geller M, Gonzalez-Estrada A, Greenberger PA, Leung AS. COVID-19 vaccine-associated anaphylaxis: A statement of the World Allergy Organization Anaphylaxis Committee. World Allergy Organization Journal. 2021 Feb 3:100517.

Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine — United States, December 14–23, 2020. MMWR Morb Mortal Wkly Rep 2021;70:46–51. DOI: http://dx.doi.org/10.15585/mmwr.mm7002e1external icon.

CDC COVID-19 Response Team; Food and Drug Administration. Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Moderna COVID-19 Vaccine - United States, December 21, 2020-January 10, 2021. MMWR Morb Mortal Wkly Rep. 2021 Jan 29;70(4):125-129. doi: 10.15585/mmwr.mm7004e1. PMID: 33507892; PMCID: PMC7842812.

Kounis NG, Koniari I, de Gregorio C, Velissaris D, Petalas K, Brinia A, Assimakopoulos SF, Gogos C, Kouni SN, Kounis GN, Calogiuri G. Allergic Reactions to Current Available COVID-19 Vaccinations: Pathophysiology, Causality, and Therapeutic Considerations. Vaccines. 2021 Mar;9(3):221.

Public Health England. COVID-19: the green book, chapter 14a.

Moghimi SM. Allergic Reactions and Anaphylaxis to LNP-Based COVID-19 Vaccines. Molecular Therapy. 2021 Mar 3;29(3):898-900.

The eating environment

Our eating environment (for example, shape and color of dinner plate, people around us, size of the food package) determines food consumption which in its turn plays a crucial role in health management. 

Technology, in particular wearables and mobile phones, may help to improve the assessment of the eating environment, the food we eat, and efficacy of dietary interventions. 

What technologies are gaining steam in this field? 

Paper-based records, web or mobile food diaries and built-in barcode scanner have enjoyed some lime light but never really picked up.

Photograph-based diaries have evolved from Amazon's Mechanical Turk based services to Ecological Momentary Assessment apps using Deep Convolutional Neural Networks and nudging chatbots. When will this technology becomes ubiquitous? Or will it be completely automatic, done for us by passive sensing tools such as wrist-based eating detectors or our walls and places we order food from? As in an Australian hospital that offered a food ordering app (electronic food service, EFS) that would also do nutritional analysis. The patients seemed to really like it. Was it because there was not much else to do in the hospital? 

Food coaching apps will only keep evolving.

REFERENCES

Sun J, Radecka K, Zilic Z. FoodTracker: A Real-time Food Detection Mobile Application by Deep Convolutional Neural Networks. arXiv preprint arXiv:1909.05994. 2019 Sep 13.

Jiang L, Qiu B, Liu X, Huang C, Lin K. DeepFood: Food image analysis and dietary assessment via deep model. IEEE Access. 2020 Feb 13;8:47477-89.

Roberts S, Chaboyer W, Hopper Z, Marshall AP. Using Technology to Promote Patient Engagement in Nutrition Care: A Feasibility Study. Nutrients. 2021 Feb;13(2):314.

Goldstein SP, Hoover A, Evans EW, Thomas JG. Combining ecological momentary assessment, wrist-based eating detection, and dietary assessment to characterize dietary lapse: A multi-method study protocol. Digital Health. 2021 Feb;7:2055207620988212.