COVID update: Masks, tests, cancer patients
April 1, 2022 | View PDF
Masks facts and Fiction
The issue of wearing a mask is different for older adults who have several medical conditions they are managing. It is not a matter of choice but of necessity. Now, scientists have a better idea of what masks can and cannot do during the current wave of the pandemic. An international research team developed a new theoretical model to better assess the risks of spreading viruses such as COVID-19, with and without a face mask. The results show how the standard ‘safe’ distance of 6 feet does not always apply but varies greatly depending on a range of environmental factors.
The current recommendations and understanding around the transmission of respiratory infectious diseases are often based on a diagram developed by the American scientist William Firth Wells in 1934. However, this model lacks sophistication and does not account for the true complexity of transmission.
Researchers developed a more advanced model to show that it is possible to more efficiently calculate the direct risk of spreading COVID infection. The new model incorporates a number of factors, such as interpersonal distance, temperature, humidity levels, viral load and type of exhalation. The researchers were able to demonstrate how these risks change with and without a face mask.
The study revealed that a person talking without a face mask can spread infected droplets three feet away. Should the same person cough, the drops can be spread up to nine feet. If the person sneezes, the spread distance can be up to 21 feet. However, using a face mask, the risk of spreading the infection decreases significantly.
“If you wear a surgical mask, the risk of infection is reduced to such an extent that it is practically negligible, even if you’re only standing one meter (3.2 feet) away from an infected person,” explained study investigator Gaetano Sardina, who is an associate professor of Fluid Mechanics at the Department of Mechanics and Maritime Sciences at Chalmers University of Technology in Sweden.
Just a saliva sample and a light
A team of researchers now has come up with a low-cost, portable, non-invasive device that uses light and saliva to test COVID-19 patients in less than 30 minutes. The results have shown that the device can detect very low concentrations of SARS-CoV-2 with a sensitivity of 91.2% and a specificity of 90%, similar to that of PCR but as fast as an antigen test.
The team developed a flow virometer, a device that uses light to detect the concentration of the virus in a liquid. The device uses a couple of drops of saliva and fluorescent light markers. When saliva is collected from the saliva of a patient’s mouth, it is added to a solution that contains fluorescent antibodies. If the saliva contains any presence of viral particles, the fluorescent antibodies will attach to the virus. In less than one minute, a reading is rendered.
The team carried out a blind test with 54 samples and were able to confirm 31 cases out of 34 positives with only three false negatives. In addition, they measured 3,834 viral copies per milliliter, which is at least three orders of magnitude lower than that of commercially available rapid antigen tests.
Responses to COVID-19 vaccines found in cancer patients on immunotherapy
Great news to report during the current wave of the pandemic: Among patients with solid tumors, those receiving immunotherapy have a more durable immune response to COVID-19 vaccination.
A new study showed less durable responses for patients with cancer receiving chemotherapy or targeted therapy. The results were presented at the ASCO Genitourinary Cancers Symposium 2022. For this study, researchers evaluated the immune response to COVID-19 vaccination in 61 patients with solid tumors who were receiving anticancer therapies.
The most common tumor types were kidney (19 patients), breast (16 patients), bladder (7 patients) and lung (7 patients). The types of anticancer therapy received included chemotherapy (29 patients), immunotherapy (19 patients) and targeted therapy (13 patients).
Most patients received the AstraZeneca vaccine (36 patients), followed by the Pfizer-BioNTech vaccine (23 patients) and the Moderna vaccine (1 patient). A second vaccine dose was administered within 12 weeks of the first dose and followed by a third booster dose.
Blood samples were collected at four time points (before the second dose, at 14-36 days after the second dose, at 36-63 days after the second dose, and within 30 days of the third dose). Between the first and second time points, there was a significant difference in the proportion of patients achieving a maximum antibody response for both the immunotherapy and targeted therapy groups, but the difference was not significant for the chemotherapy group.
Before the second dose, a maximum response was seen in 21% of patients in the immunotherapy group, 15% in the targeted therapy group, and 24% in the chemotherapy group. At 14-36 days after the second dose, a maximum response was seen in 83% of patients in the immunotherapy group, 69% in the targeted therapy group, and 54% in the chemotherapy group.
Within 30 days of a third dose, a maximum response was seen in 93% of patients in the immunotherapy and chemotherapy groups and 100% of patients in the targeted therapy group.
“Immunologic response to COVID-19 vaccination is dependent on the type of systemic anticancer therapy,” the researchers concluded. “The third booster vaccine dose appears particularly relevant for chemotherapy patients, compared to those receiving immune therapy or targeted therapies. COVID-19 shielding guidelines and booster dose guidance should be tailored according to treatment group.”