Its not clear if immunity to one strain confers immunity to other strains…
Not all disease experts agree on the data-if the virus is mutating enough to change how contagious it is that is bad enough, but if the virus is also mutating and changing its surface proteins then that is very bad…

A research paper from scientists at Los Alamos National Laboratory, not yet peer-reviewed, reports that one strain of the novel coronavirus has emerged in Europe and become dominant around the planet, leading the researchers to believe the virus has mutated to become more contagious.

The bold hypothesis, however, was immediately met with skepticism by many infectious-disease experts, and there is no scientific consensus that any of the innumerable mutations in the virus so far have changed the general contagiousness or lethality of covid-19, the disease caused the coronavirus.

The Los Alamos scientists, led by computational biologist Bette Korber and working in conjunction with researchers at Duke University and the University of Sheffield in the United Kingdom, examined a global database of strains of SARS-CoV-2, the virus that causes the disease. According to their analysis, one strain featuring a mutation dubbed Spike D614G quickly out-competed other strains after it appeared in Europe.

The mutation affects the structure of a protein, called the spike protein, that is critical to the virus’s ability to infect human cells. The researchers believe this structural change enhances infectivity.

“The mutation Spike D614G is of urgent concern; it began spreading in Europe in early February, and when introduced to new regions it rapidly becomes the dominant form,” the authors write. They describe the mutation “increasing in frequency at an alarming rate, indicating a fitness advantage relative to the original Wuhan strain that enables more rapid spread.”

The paper will now have to survive the intense scrutiny of a research community trying to deliver urgently needed information while remaining scientifically rigorous.