The following is my opinion, as a Roman Catholic author of several books on the End Times, including a book specifically on Garabandal and Medjugorje.
Is Covid-19 related to the Warning of Garabandal?
Covid-19 is the official name of the disease that people call the Coronavirus. This disease pandemic is not “the Warning”. The Warning of Garabandal was described by the visionaries as God showing everyone the sins on their conscience. Some have suggested that the pandemic was a way to keep everyone in their homes, to facilitate the Warning — but that did not happen. The Warning will almost certainly occur on Good Friday some year. (In my eschatology books, I speculate it will be the year 2022.)
What might the relationship be between Covid-19 and the Warning? I don’t see any direct relationship. I don’t believe the pandemic will still be affecting the world by Good Friday of 2022. There does not seem to be a direct relationship between those two events, the pandemic and the Warning.
Is Covid-19 related to the End Times?
Yes, it is related. However, in my opinion, the End Times have not yet begun. What we have been experiencing, since the year 2000, has been the threshold of the Tribulation (the Apocalypse; the End Times) — a set of preparatory events. The pandemic is one such event. It has caused people to be prepared for future pandemics, which will occur during the End Times and which will be much worse. It has caused people to store up food and supplies, which will help them during the much more severe events of the End Times. And it is itself a punishment from God for sin. If you are a devout Catholic, you know the sins of the world and how bad things have become, from a spiritual point of view. The pandemic is a punishment from God.
However, people are not punished each to the extent required by their sins (as occurs in Purgatory and in Hell). There are many grave sins in the world, generally, and so God permits great suffering, generally. Sometimes the worst sinners suffer less and the faithful suffer more.
If God were to cause everyone to suffer, just as much and only as much as they deserve, in a world of 7.6 billion persons, He would have to become very controlling. He would have to control pretty much your whole day, every day of your life. Is that what you want? God allows suffering so that He can allow us to live our lives as we choose — which implies the possibility of suffering.
But I also assure you that the world suffers far less than it would if God stepped back and did nothing. God has intervened innumerable times, in hidden ways, to lessen the sufferings of the world. His Providence will make certain that the harm of the pandemic is limited. But the best way to limit the harm of the pandemic is to cooperate with the grace of God, repent from sin, do good to those who are suffering, pray and practice self-denial.
RLCJ
the reproach of Christ 
Presently activating the 1st part of Isaiah 24. Main cities are closed. No entrance to the houses.
I agree God is punishing humanity to a certain degree the earth has been desecrated by man,s greed whole species of flora and fauna made extinct by our insatiable greed I believe the earth is crying out for justice not to mention the human toll of misery countless millions live in.
Did you mean: ‘But I also assure you that the world Suffers far MORE (not less) than it would if God stepped back and did nothing.
No, the world suffers less due to God’s intervention; the world would suffer more if God did nothing.
Father Regis Scanlo, Catholic Priest, wrote a very interesting article in August 2019, about the End Times.. Father Richard Heilman, RomanCatholicMan.com then added on to the article and I did a copy and paste below if you choose to add this comment for your readers. However, I agree with you Ron that we are at the threshold. I believe The Warning of Garabandal will be on Good Friday, 2022. We have just less than 2 years. These next 2 years things could get progressively worse for the World with pandemics, earthquakes, and famine. Locusts are swarming through Africa. The visionaries did states that things will be at their worst before the Tribulations begin.
‘In Fr. Scanlon’s article, he lays out a timeline:
October 13, 1884 – Pope Leo XIII heard what he believed to be the voice of Satan challenging God by saying that he can destroy the Church if he had 100 years and a greater power. This was when Pope Leo XIII wrote the Prayer to St. Michael. Satan’s “greater power” would not come from an increase in his power, but through our decreased “supernatural faith.”
October 13, 1917 (33 years later to the day, the span of Christ’s lifetime) – Miracle of the Sun at Fatima. Our Lady asks for the rosary and penance, against the errors of Russia and sins of the flesh. On October 13, 1917, the Bolshevik Revolution erupted, which sought to conquer the world through secular atheism.
In regard to Our Lady’s warning against sins of the flesh, Fr. Scanlon wrote:
“Our Lady Fatima said that Catholics must pray the daily Rosary and do penance so that people will stop offending God. Our Lady told little Jacinta that “the sins of the flesh” were the most frequent sins committed by people leading them to eternal punishment. If God was offended by these sins in 1917, how much more is He offended today? In 1917, it’s fair to say that “the sins of the flesh” were considered deviant behavior, but today the situation is far worse, because those sins, including pornography, masturbation, contraception, fornication, adultery and sodomy, are considered normal behavior. And, abortion, which is often done to cover up the “sins of the flesh,” was considered rare in 1917, but just from 1980 until today the global number of babies that have been aborted is 1.5 billion. The point here is that mankind has not only refused to repent of its “sins of the flesh,” it has even doubled down by expanding these sins in both kind and number exponentially.”
October 13, 1973 (The year Roe v. Wade gave a legal right to kill children) – Our Lady appeared in Akita, Japan to Sr. Agnes Sasagawa. Again, she asks us to pray the rosary, to do acts of penance, and to pray that the bishops stand against the sins of the flesh.
Fr. Scanlon believes (as do I) the 100 years of the unbinding of Satan began with the Miracle of the Sun. This would bring us to October 13, 2018. However, Fr. Scanlon points out that the “Extraordinary Jubilee Year of Mercy” (2015-2016) Satan was, in essence, put on hold. This adds one more year. “That brings us to a new deadline,” Fr. Scanlon wrote, “for Satan’s 100 year of power — the approaching date of Oct. 13, 2019.” And so, as Fr. Scanlon prophetically wrote (recall, he wrote this on August 12, 2019):
“According to this interpretation, if the leaders of the Church and nations have not opposed these ‘sins of the flesh’ by Oct. 13, 2019, sometime after Oct 13, 2019, God will stop Satan with a chastisement which will bring mankind to its knees.”
I would add this to Fr. Scanlon’s timeline (as these occurred after his writing):
October 6, 2019, the Vigil of Our Lady of the Rosary – Sr. Agnes Sasagawa receives another message, which is the first since 1973. Our Lady’s “Jonah like” message to Sr. Sasagawa was to “put on ashes and pray a repentant rosary.”
November 17, 2019 (There are 40 days between October 7 “Our Lady of the Rosary” & November 17, just like the “40 days warning” Jonah gave the Ninevites) – The first case of the coronavirus.
So, here we are. A global pandemic, when much of the world is terrified in lock-down. Not only is the world fearful of this pandemic, but the worldwide economy is threatened to collapse. Yes, this is a chastisement that, as Fr. Scanlon wrote, is bringing mankind to their knees. Hopefully, kneeling in prayer to the God so many have ignored for so long.
How can the bishops mitigate this chastisement? How can they heed the call to stand against the sins of the flesh? They cannot wave a magic wand that heals us all from sins of the flesh. But, they do have tools at their disposal. The bishops must “take stock,” and work, fervently, to restore supernatural faith.’