Coronavirus science | Week in review: Vaccine registration, blood sugar dangers, and Covid severity



READ | Even if you’re not diabetic, high blood sugar could be fatal with Covid-19

The deadly impact of Covid-19 on diabetic patients has been well-established during the coronavirus pandemic, but more research is showing that high blood sugar can be fatal, even if you don’t suffer from diabetes.

Earlier research in July first revealed this sinister complication in coronavirus patients, and the latest study from Spain is the largest to date, using data from more than 11 000 patients.

Published in Annals of Medicine, the study took a closer look at the blood sugar levels of Covid-19 patients at the time of their hospital admission, regardless of their diabetic status.

The researchers established that high blood sugar – also known as hyperglycaemia – upon non-critical admission is an early warning sign that a Covid-19 patient might need mechanical ventilation and have a higher risk of death.

In those without diabetes, hyperglycaemia can be triggered by infection, trauma, medications and other chronic conditions.

"Although several studies and meta-analyses have shown that patients with diabetes have a significantly higher risk of severe Covid-19 and increased mortality rates," write the researchers,"the impact of hyperglycaemia itself, rather than the presence of [diabetes], has not been sufficiently described in non-critical patients hospitalised with Covid-19".

One theory suggests that the virus’s infection of endocrine pancreas cells can disrupt the body’s insulin management, while another highlights that the inflammation a body endures during an infection can increase insulin resistance."One question that remains to be answered is whether hyperglycaemia plays any role in the physiopathology of the disease or if it is just an inflammatory bystander," the study speculates.

READ | Sex steroids could explain why Covid-19 is more severe for men than women

In most societies around the world, women tend to outlive men. In the Covid-19 pandemic, that demographic quirk is even more pronounced as men are twice as likely as women to suffer from severe complications from the coronavirus.

Earlier research into this phenomenon has highlighted differences in antibodies, immune responses that control inflammation and circulating proteins. But discovering why these differences exist has been an ongoing quest for the science community.

A new study published in Trends in Endocrinology and Metabolism however looks at one of the key differences between men and women’s biology - sex steroids. Women have higher levels of oestrogen, progesterone, and allopregnanolone important in the process of reproduction.

But these steroids aren’t just for making babies - they also manage and control inflammation in the body, which is one of Covid-19’s biggest weapons against the human body.

Progesterone, alongside another steroid oestradiol, also has neural influences, act as anti inflammatories, can boost immune cells and increase antibody production. This helps pregnancies be more viable without being labelled as intruders in the woman’s body. And when the body is under stress from a virus, it can trigger self-healing in respiratory cells - exactly where SARS-CoV-2 likes to proliferate - and increase T-cell production to fight off the infection.

“In females, a faster recovery of the lung tissue may reduce the susceptibility to secondary bacterial infection, which is the primary cause of mortality after influenza virus infection,” explain the researchers.

“This finding is substantiated by studies showing that following influenza A virus infection, the histological density of pulmonary inflammation was decreased during pregnancy.”

READ | Covid-19: How vaccine registration will work in SA

Over a hundred vaccine candidates are under development for Covid-19 globally. Twelve of these are undergoing large-scale phase III clinical trials to assess their safety and efficacy.

Vaccines being developed by BioNtech/Pfizer,Moderna and Oxford University/AstraZeneca all appear to be highly effective based on preliminary findings - although not all effective vaccines will necessarily be appropriate for use in South Africa.

As more evidence for competing vaccine candidates becomes available, South Africa’s National Essential Medicines List Committee will need to review available evidence and identify which roducts are appropriate for use in our public health sector.

As it is anticipated that initial vaccine supply will be limited and prices may be prohibitive, South Africa will need to identify priority populations for initial vaccination.

The Ministerial Advisory Committee is developing recommendations for the Minister of Health, Dr Zweli Mkhize, on who should be prioritised for initial vaccination and how vaccines should be delivered to priority populations.

But before any vaccines can be delivered to priority populations - or marketed through the private sector- their use must be authorised by the South African Health Products Regulatory Authority (SAHPRA).

Director of Affordable Medicines at the National Department of Health, Khadija Jamaloodien, explains that “South Africa has a well-respected Regulatory Authority (SAHPRA) and that in terms of Section 14 of the Medicines and Related Substances Act, no medicine may be sold in the country unless it is registered by SAHPRA”.

“This would apply to vaccines as well.”

SAHPRA, which replaced South Africa’s former medicines regulator (the Medicines Control Council [MCC]) in 2018, ensures that all medicines (including vaccines) that are distributed and marketed in the country are safe, effective and of good quality. Before medicines can be provided in the public sector, or sold through private sector facilities, they must be registered by SAHPRA.

READ | Existing treatments continue to be looked at for Covid-19: Latest science on BCG and the MMR vaccine

Scientists have been looking at existing vaccines to see whether they could also induce protection against Covid-19, the disease caused by SARS-CoV-2. Among them are the measles-mumps rubella (MMR) vaccine, as well as the decades-old tuberculosis vaccine, Bacillus Calmette-Guérin (BCG).

In a new study published in mBio, an open-access journal of the American Society for Microbiology, researchers provide evidence that in the MMR vaccine, mumps IgG titers (also known as levels of IgG antibody) are inversely correlated with severity in recovered Covid-19 patients previously vaccinated with the MMRII vaccine produced by Merck.

And, according to a new study by Cedars-Sinai, BCG is associated with reduced likelihood of contracting Covid-19. The study was published in the Journal of Clinical Investigation.

The MMR vaccine has been looked at as a possibility to work against Covid-19 since the early months of the pandemic, as it is known to protect against viruses that are similar to the coronavirus.

The World Health Organization (WHO) states that the vaccine is widely used for the immunisation of children in certain regions of the world due to its advantages over individual vaccines.

The vaccine, which was developed almost 50 years ago, has since been received by hundreds of millions of people worldwide.

Countries involved in a study launched earlier this year include Canada, Ghana, Ireland, South Africa, Uganda, the UK, the US, Zambia and Zimbabwe, Health24 reported.

“... This type of vaccine, which contains small amounts of very weakened measles, mumps and rubella viruses, appears to strengthen the body’s immune response to infections in general, not just to the viruses in that particular vaccine,” said Sinead Delany-Moretlwe, one of the SA trial’s national principal investigators, and a research professor at the Wits Reproductive Health and HIV Institute (Wits RHI).

Another reason it may be effective is that there are similarities between the weakened viruses in the vaccine and the Covid-19 virus, Delany-Moretlwe explained.

About the more recent study, lead study author Jeffrey Gold, president of World Organization in Watkinsville, Georgia, said: "We found a statistically significant inverse correlation between mumps titer levels and Covid-19 severity in people under age 42 who have had MMR II vaccinations.


SA cases update: 

The latest number of confirmed cases is 787 702.

According to the latest update, 21 477 deaths have been recorded in the country.

There have been 730 633 recoveries.

Global cases update:

For the latest global data, follow this interactive map from Johns Hopkins University & Medicine.

Late on Sunday night, positive cases worldwide were over 62.5 million, while deaths exceeded 1.4 million.

The United States had the most cases in the world - just over 13.3 million as well as the most deaths - more than 266 000.


Latest news:

HEALTH TIPS (as recommended by the NICD and WHO)

• Maintain physical distancing – stay at least one metre away from somebody who is coughing or sneezing

• Practise frequent hand-washing, especially after direct contact with ill people or their environment

• Avoid touching your eyes, nose and mouth, as your hands touch many surfaces and could potentially transfer the virus

• Practise respiratory hygiene – cover your mouth with your bent elbow or tissue when you cough or sneeze. Remember to dispose the tissue immediately after use.

Image credit: Getty Images

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