With inputs from Dr Monica Vasudev

994:   When the prevalence of COVID-19 is high, even atypical imaging features are more likely to be COVID-19.

995: Typical chest CT findings in COVID-19 pneumonia include bilateral, peripheral and basal-predominant ground-glass opacities (GGOs) and/or consolidation, followed later by a mixed pattern of crazy paving, architectural distortion and perilobular abnormalities superimposed on GGOs that slowly resolve.

996: Upper lobe or peribronchovascular distribution of GGOs, cavitation, lymphadenopathy, and pleural thickening are found atypically.

997: Other viral pneumonias can be more challenging to distinguish from COVID-19. For example, GGOs can be evident in up to 75% of adenovirus cases, more than 75% of cytomegalovirus and herpes simplex virus cases, and up to 25% of measles and human meta-pneumovirus cases. GGOs can be widespread in pneumocystis pneumonia, but, unlike in COVID-19, they tend to predominate in the upper lobes.

998: GGOs can also be common in hypersensitivity pneumonitis, lung injury from use of electronic cigarettes or vaping products, pulmonary edema, diffuse alveolar hemorrhage, pulmonary alveolar proteinosis, and eosinophilic pneumonia. But clinical features and GGO patterns are generally useful for differentiating these conditions from COVID-19.

999: Scientists in Singapore have discovered T cell immunity specific to SARS-CoV-2 among recovered COVID-19 and SARS patients, as well as in uninfected individuals. T cells, in conjunction with antibodies, form a part of the human immune response against viral infections. T cells target and kill infected cells. The study, published in Nature, noted specific T cells in all those who recovered from SARS 17 years ago, and in more than 50% of both SARS-CoV-1 and SARS-CoV-2 uninfected individuals tested. A level of pre-existing SARS-CoV-2 immunity thus seems to be present in the general population. The investigators concluded that infection and exposure to coronaviruses generates long-lasting memory T cells, which could assist with the management of the current pandemic. This could be attributed to cross-reactive immunity from exposure to other coronaviruses, such as those causing the common cold. It is important to determine if this could explain why some individuals better control the infection. [Source: Duke-NUS Medical School]

1000: The incidence of stillbirth has been found to have increased since the COVID-19 pandemic began in a comparative study of pregnancy outcomes in a London hospital. This could have been due to indirect effects such as unwillingness to attend hospital when needed (e.g., with reduced fetal movements), fear of contracting infection, or not wanting to add to the National Health Service burden, suggested Dr Asma Khalil of St Georges University of London in JAMA.

1001: A phase I/II trial of a vaccine against SARS-CoV-2 under development by the University of Oxford has revealed that the vaccine is safe, causes few side effects, and incites strong immune responses. Early stage results, published in The Lancet, have noted that the candidate vaccine triggered a T-cell response that peaked 14 days following vaccination, and an antibody response within 28 days. The trial has included 1077 healthy adults thus far, and revealed minor side effects compared with a control group given a meningitis vaccine. The most commonly reported reactions included fatigue and headache. There were no serious adverse events. The chimpanzee adenovirus viral vector vaccine (ChAdOx1) against the COVID-19 coronavirus is developed at Oxford University.

Phase II data on a competing vaccine from China, which is also using an adenovirus vector to deliver a gene encoding SARS-CoV-2 antigen, suggested that the product could be effective.

Phase I results on Modernas mRNA vaccine also suggest that a vaccine, possibly more than one, could soon be within reach.

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA