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Herd immunity can be achieved by letting the virus spread through the population

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Herd immunity is a key concept for epidemic control. It states that only a proportion of a population needs to be immune (through overcoming natural infection or through vaccination) to an infectious agent for it to stop generating large outbreaks.1 A key question in the current COVID-19 pandemic is how and when herd immunity can be achieved and at what cost. Herd immunity occurs when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely.

Acquired immunity is established at the level of the individual, either through natural infection with a pathogen or through immunization with a vaccine. It refers to the indirect protection from infection conferred to susceptible individuals when a sufficiently large proportion of immune individuals exist in a population. This population-level effect is often considered in the context of vaccination programs, which aim to establish herd immunity so that those who cannot be vaccinated, including the very young and immunocompromised, are still protected against disease.

As a result, the whole community becomes protected — not just those who are immune. However, there are some significant problems with relying on community infection to create herd immunity to the virus that causes COVID-19.2First, it isn’t yet clear if infection with the COVID-19 virus makes a person immune to future infection. If it does not create immunity, herd immunity will not work.

Even if COVID-19 infection creates long-lasting immunity to coronavirus, a large number of people would have to become infected to reach the herd immunity threshold. Experts estimate that 70% of the population would have to recover from COVID-19 to halt the epidemic.3 On a separate related note, this amount of infection could also lead to serious, and potentially long-term, complications and millions of deaths. If many people become sick with COVID-19 at once, the healthcare system could quickly become overwhelmed.

It is therefore advisable to continue to use these practices to reduce the spread of COVID-19:

  • Wear a mask in public.
  • Keep your physical distance — 6 feet or about two arms’ lengths apart from other people.
  • Avoid in-person gatherings.
  • Wash your hands with soap and water.
  • Stay home if you do not feel well.
  • Get a test if you have COVID-19 symptoms.
  • Self-isolate if you have been around someone who is sick or tested positive.

Source

1 Fontanet A, Cauchemez S. COVID-19 herd immunity: where are we? Nat Rev Immunol. 2020;20(10):583-84. doi: 10.1038/s41577-020-00451-5.
2 Randolph HE, Barreiro LB. Herd Immunity: Understanding COVID-19. Immunity. 2020;52(5):737-41. doi: 10.1016/j.immuni.2020.04.012.
3 https://www.jhsph.edu/covid-19/articles/achieving-herd-immunity-with-covid19.html

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Coronavirus

It is safe to mix Sputnik V & Covishield Doses

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Over the past few months, a lot of stories have been on the mix and match of vaccine cocktails, partly to curb the crisis of vaccines in India and partly to understand if the mixing can actually fortify the efficacy of the vaccines. Across the globe, several countries have already started testing out ‘vaccine cocktails’ in the hope that if one vaccine is less effective against a variant, then one can get a booster shot of another vaccine that could have a higher efficacy against a variant.

The Covid-19 working group of the National Technical Advisory Group on Immunisation (NTAGI) is considering allowing the mixing vaccines, but with a clause that both doses will have to be from same platforms.

The NTAGI Chairman Dr. NK Arora clarified that this would mean that Covishield could be taken in combination with Sputnik, since both are adenoviral platform vaccines. Similarly, once available, Pfizer and Moderna vaccines could be taken in combination as they are mRNA vaccines.

However, the NTAGI Chairman still encouraged administering two doses of the same vaccine as currently the NTAGI has not made any formal recommendation to the government so far.

Minister of State for Health Dr. Bharati Pravin Pawar has also clarified that mixing doses of COVID-19 vaccines is not yet the protocol in India.

The Subject Expert Committee of the Central Drugs Standard Control Organisation (CDSCO) had also recommended conducting a clinical trial into the effects of combining Covaxin and Covishield just last week, but updates are awaited on the same.

In many European countries, including Germany, France, Sweden, Norway and Denmark, authorities are now advising younger people, who were previously given the AstraZeneca vaccine as a first dose, to take an alternative vaccine as their second vaccine jab. 

Health officials in Canada are now advising Canadians to combine either the AstraZeneca-Oxford, Pfizer-BioNTech or Moderna shots interchangeably in certain situations. Canada’s National Advisory Committee on Immunization (NACI) updated its latest guidance and recommended that a first shot of the AstraZeneca vaccine can be followed by either Moderna or Pfizer.

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Coronavirus

SARS-CoV-2 is engineered to cause a pandemic

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After our coverage of the debates going around the world on the hot topic if Coronaviruses are lab generated or escaped from a laboratory in China, we have received many questions around the subject. One question of particular interest is if the SARS-CoV-2 is engineered to cause a pandemic. Well, the jury is still out on this one, but we are trying to collate as much data to bring to you authentic information surrounding this news going around the world about a lab-engineered virus, powerful enough to cause a pandemic.

A review published in the journal Naturelooks at the key arguments that support a lab leak, and the extent to which research has answers. According to them just because the virus spreads among humans does not automatically translate to mean that it was designed to do so. It also flourishes among mink and infects a host of carnivorous mammals. In fact, over the last year, since the Delta variant mutated to form the Delta Plus variant, it has been seen that the virus is capable of multiplying on its own outside any laboratory or without the aid of scientists working on different variants.

Theories speculating all over the web, the scientific community and the top offices of various nations back the speculation that the virus was engineered to cause this pandemic because three staff members at the Wuhan Virology Laboratory were sick in November 2019 itself before the first cases of COVID-19 were reported in China in December 2019. Also, during the initial days of the pandemic, we were made aware of similar viruses that have been found in wild bats, which have still not been ruled out as the origin and then infection via an intermediate host. Even the SARS and MERS came from bats, so there are genuinely many reasons to still not conclude that this is an engineered virus and could have been an accident.

Throwing more light on the subject, a study published in the journal Emerging Microbes & Infections, researchers led by Shan-Lu Liu at the Ohio State University have reported that there is “no credible evidence” of genetic engineering and that the virus’s genome has been sequenced for analysis. If this were true that the virus was engineered, the signs of engineered or inserted gene sequences would have been evident. But as we clearly have seen, are scattered in a random way, just as they would be if the new virus had evolved naturally.

Meanwhile, in July end 2021, amid demands of investigating the origin of Coronavirus in China, the World Health Organisation has said that while no country can be compelled into divulging more data on Covid origin, a second phase of studies is needed to understand the virus’ origin and should begin soon. 

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Coronavirus

Coronavirus escaped from a lab in China

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Every week there is a new theory for the first appearance of the Coronavirus and the investigation into the origin of the pandemic. While most scientists say Coronavirus has a natural origin in all probability, and was transmitted from an animal to humans, the debate over whether this was a lab leak has not been concluded yet.

A lot of industry experts and world leaders have been calling for a deeper investigation into the hypothesis that the virus emerged from the Wuhan Institute of Virology (WIV), located in the Chinese city where the first COVID-19 cases were reported. For e.g., in May this year, US President Joe Biden tasked the US Intelligence Community to join efforts to find SARS-CoV-2’s origins, whatever they might be, and report back in 90 days. Australia, the European Union and Japan have also called for a robust investigation into SARS-CoV-2’s origins in China.

A lot of infectious-disease researchers are also of the opinion that the virus evolved naturally and spread from a bat either directly to a person or through an intermediate animal. Bats are known carriers of coronaviruses, and scientists have determined that the genome of SARS-CoV-2 is most similar to that of a coronavirus that was first detected in a variety of bats found in the southern Chinese province of Yunnan in 2013.

HIV, influenza epidemics, Ebola outbreaks and the coronaviruses that caused the SARS epidemic beginning in 2002 and the Middle East respiratory syndrome (MERS) outbreak beginning in 2012 have all shown that emerging infections begin with a spillover from nature but the possibility that the SARS-CoV-2 escaped from a lab can still not be ruled out.

A detailed overview of the for and against lab leak theory has been discussed in the journal Nature, that states that the SARS-CoV-2 could have come from a lab in a few ways, including the possibility that the researchers may have collected SARS-CoV-2 in their lab to study, or created it by engineering coronavirus genomes. This may have led any of them to be infected with the virus deliberately for experiment or accidentally, thus spreading it further and becoming the possible origin of the pandemic.

The fact that the SARS-CoV-2 was first detected in Wuhan, where a top lab is studying coronaviruses does tend credibility to the speculation that the pandemic origins may be through a leak in the labs. A similar discussion has suggested that SARS-CoV-2 might have derived from coronaviruses found in an unused mine where WIV researchers collected samples from bats between 2012 and 2015 and the current pandemic is a result of either those experiments gone wrong or an accidental slip that could not be contained in time.

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Fact Check

Drinking lemon water can help lose weight

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Most nutrition experts and diet specialists recommend starting your day with a glass of warm water with lemon squeezed in. A lot of people desirous of losing weight follow this religiously. But does it really aid fullness or lead to weight loss? There is a slim chance it may but there are no direct studies providing evidence for this claim.

Studies suggest water can help feel full and decrease your calorie intake which can lead to weight loss. Although most of these studies focus on regular water, experts believe the same results apply to lemon water as well. A study aimed at assessing the effects of water on calorie intake in 24 overweight and obese older adults reported that drinking 500ml water before breakfast led to a 13% reduction of calorie intake.  Similarly, another study showed that drinking water with a meal not only decreased hunger, but also increased fullness during the meal.

Scientists believe that since lemon water is low in calories and promotes fullness the same way as regular water, it can be an effective way to help reduce calorie intake. This may in turn lead to effective weight loss if followed for a longer period of time. However, due to lack of evidence for lemon water per se, it cannot be specifically said that lemon water helps you reduce weight.

Lemon water has also been tested in studies due to its effects on metabolism, fullness, and hydration, if it could enhance weight loss as well. In one study, 48 adults were assigned to two diets: a low-calorie diet with 500ml of water prior to each meal or a low-calorie diet with no water before meals. Results of the 12-week study, participants in the water group had lost 44% more weight than participants in the non-water group. Similarly, another study analyzed the water intake in 173 overweight women and found that water intake directly correlated with loss of body weight and fat, regardless of diet or physical activity.

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Coronavirus

Coffee a day may keep Coronavirus at bay

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If you are like our editorial team, you cannot imagine starting your day without a large cup of coffee! Besides giving a much-needed energy boost, coffee is like fuel to quite a few people in the world – something that keeps them going. Well, there is more good news for these people.

A recent study conducted by researchers from Northwestern University discusses how persons who drink coffee have fewer chances of contracting the deadly COVID-19 virus. The study evaluated data of 40,000 adults in the UK Biobank and looked at the link between diet factors including daily intake of coffee, tea, oily fish, processed meat, red meat, fruit, and vegetables, and Covid. They found that consumption of at least 0.67 servings/d of vegetables (cooked or raw, excluding potatoes) was also associated with a lower risk of Covid-19 infection.

The research is first of its kind on caffeine benefits and actually concludes that people who consume at least one cup of coffee a day have nearly 10% less chance of getting infected by the coronavirus. The study also added that taking coffee more than a cup is an added bonanza for the person.

Researchers of the study added that consumption of coffee positively associates with inflammatory biomarkers such as C-reactive protein, tumor necrosis factor I (TNF-I) and interleukin-6 (IL-6), which are also associated with coronavirus severity, which could probably be the logic behind this study result. Not only COVID-19 infection, but the study also states that consuming coffee was associated with lower risk of pneumonia in elderly. If coffee is taken on a regular basis, it would have an immunoprotective effect against the fight of the deadly virus.

The study thus supports the hypothesis that has been followed by many since the pandemic began that nutritional factors may influence distinct aspects of the immune system, hence the risk factors responsible for contracting Covid-19. The study researchers also suggested that adherence to higher vegetable intake and reducing processed meat intake could be an added advantage in tackling and restricting the spread of coronavirus.

Good ideas start with brainstorming. Great ideas start with coffee – Coffee Mill

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