COVID-19: What you need to know about the coronavirus pandemic on 19 May

1. How COVID-19 is affecting the globe

Confirmed cases of COVID-19 have passed 164.2 million globally, according to Johns Hopkins University. The number of confirmed deaths stands at more than 3.4 million. More than 1.5 billion vaccination doses have been administered globally, according to Our World in Data.

Brazil recorded 75,445 additional confirmed cases of the coronavirus on Tuesday, along with 2,513 new deaths from COVID-19, Health Ministry figures showed. Brazil has now registered 15.73 million cases since the pandemic began, and the official death toll stands at 439,050, according to ministry data.

Taiwan will get 400,000 more AstraZeneca Plc (AZN.L) COVID-19 doses on Wednesday from the COVAX global sharing programme, the government said, as it faces a dwindling supply of shots during a spike in infections.

India's daily death toll rose to a record 4,529 on Wednesday, with 267,334 new coronavirus infections over the last 24 hours. The total case tally is now 25.5 million.

South Africa has begun to vaccinate over-60s after it signed large supply deals with Pfizer and J&J for a combined 61 million doses.

The United States has administered more than 275.5 million doses of COVID-19 vaccines in the country as of Tuesday morning and distributed more than 346.6 million doses, the U.S. Centers for Disease Control and Prevention said.

The country administered COVID-19 vaccinations to around 600,000 children ages 12 to 15 last week after regulators cleared Pfizer/BioNTech shots for use in that age group, U.S. Centers for Disease Control and Prevention Director Rochelle Walensky said .

2. Vaccines could alleviate the symptoms of long COVID, new research suggests

A new survey conducted by the advocacy group LongCovidSOS compared the symptoms of 812 people across the world suffering from long COVID before and after they received their first vaccine dose.

The participants, who were predominantly white females from a variety of countries suffering from 'long COVID', were asked to score the severity of 14 long COVID symptoms before and after receiving a first vaccine dose.

The study, which is yet to be peer-reviewed, found that 56.4% of the respondents experienced an overall improvement in their symptoms with 24.6% experiencing no change and 18.7% experiencing a deterioration in their symptoms.

In general, those who received mRNA vaccines such as Pfizer/BioNtech or Moderna, reported more improved symptoms.

“This survey will reassure people that they would have to be quite unlucky to really have an overall worsening of symptoms,” analysis author Ondine Sherwood of LongCovidSOS told the Guardian. “The data is very encouraging, but we don’t know how long the benefits last.”

It is unclear whether the data proves that vaccines are responsible for improved symptoms, but it could pave the way for future treatments for sufferers of long COVID.

3. AstraZeneca vaccine followed by Pfizer dose safe and effective, Spanish study finds

A Spanish study on mixing COVID-19 vaccines has found that giving a dose of Pfizer's drug to people who already received the first shot of the AstraZeneca vaccine is highly safe and effective, preliminary results showed on Tuesday.

The Combivacs study, run by Spain's state-backed Carlos III Health Institute, found the presence of IgG antibodies in the bloodstream was between 30 and 40 times higher in people who got the follow-up Pfizer shot than in a control group who only received one AstraZeneca dose.

Meanwhile, the presence of neutralising antibodies rose seven-fold after a Pfizer dose, significantly more than the doubling effect observed after a second AstraZeneca shot.

Around 670 volunteers between the ages of 18-59 who had already received a first dose of AstraZeneca's vaccine participated in the study, with some 450 given a Pfizer dose.

Just 1.7% of the participants reported severe side effects, which were limited to headaches, muscle pain and general malaise, said Dr Magdalena Campins, one of the study's leaders.

"These are not symptoms that can be considered serious," she said.

Spain embarked on the study to determine how best to proceed after limiting AstraZeneca's shot to people aged over 60 due to concerns about blood clotting.